fix(portal): per-challenge SSH user in web terminal + credential API

The web SSH terminal and the credential API reported `ctfuser` for all 16
challenges, but only the 6 native GEMASTIK XVIII images provision ctfuser.
Every imported XVI/XVII image does `RUN echo root:${PASSWORD} | chpasswd`,
so 10 of 16 participant logins were refused with "Permission denied".

Root causes (all the same class of bug - login hardcoded in the wrong layer):
- main.py websocket ssh handler read st["ssh_user"], a single team-wide value
  defaulting to ctfuser, instead of the per-challenge registry field
- /api/credential proxied the global receiver on :18080, which only knows the
  6 native challenges, so the other 10 returned "Invalid challenge"
- team.html hardcoded the challenge picker to those same 6 challenges, making
  the other 10 unreachable from the terminal entirely
- index.html rendered `<b>ctfuser</b>` and a stale hardcoded SSH port table

Fixes:
- orch.challenge_credential()/all_teams() read the TEAM's state.json, which
  holds the same per-challenge password the panel chpasswds
- gen_receiver_services.py injects SSH_USER_<port> from the registry so the
  receiver's /credential endpoint agrees with the panel
- receiver Challenge.credentials() honours SSH_USER_<port> (ctfuser fallback)
- new /api/team/{idx}/own-challenges feeds the picker; targets now carry
  challenge + ssh_user
- UI takes user and port from the server instead of hardcoding them

Verified: 32/32 credential payloads correct across teams 1-2, and 32/32 real
paramiko SSH logins succeed with whoami confirming the expected account.

Also adds bulk team delete: POST /api/teams/bulk-delete runs one background
thread and is polled via GET /api/teams/bulk-delete/{job_id}, plus per-team
checkboxes with select-all/clear in the UI. Deletion must stay sequential
because delete_team() regenerates shared artifacts at the end.

panel/static/index.html

@@ -171,6 +171,12 @@
       <button class="danger" onclick="stopAllTeams()">⏹ Stop CTF (semua)</button>
     </div>
   </div>
+  <div id="bulkDelBar" style="display:none;margin:10px 0"></div>
+  <div class="card" style="margin-bottom:10px;display:flex;gap:10px;align-items:center;flex-wrap:wrap">
+    <button onclick="selectAllTeams(true)">☑️ Pilih semua</button>
+    <button onclick="clearTeamSelection()">☐ Kosongkan</button>
+    <span style="font-size:11px;color:#718096">Centang tim di kiri nama untuk hapus massal sekaligus</span>
+  </div>
   <div class="grid" id="teamsGrid"></div>
   <div class="card" style="margin-top:16px">
     <div class="team-head">
@@ -445,6 +451,11 @@ async function toggleChallenge(name, enabled) {
   }
 }
 // ---------- Challenges ----------
+// The admin challenge grid is a global node view with no team of its own, so it
+// asks for credentials without ?team= and the server falls back to the receiver.
+// Team-scoped pages pass their own index instead.
+function TEAM_Q() { return ''; }
+
 async function refresh() {
   const grid = document.getElementById('grid');
   try {
@@ -474,9 +485,11 @@ async function refresh() {
           <button onclick="viewCred('${esc(ch.name)}')">SSH</button>
         </div>
       </div>`;
-      fetch(`/api/credential/${ch.name}`).then(r=>r.json()).then(c => {
+      fetch(`/api/credential/${ch.name}${TEAM_Q()}`).then(r=>r.json()).then(c => {
         const el = document.getElementById('creds-' + ch.name);
-        if (el && c.username) el.innerHTML = `<b>ctfuser</b> / <b>${esc(c.password)}</b>`;
+        // Use the username the server reports: it is per-challenge (ctfuser for
+        // the 6 native XVIII images, root for the imported XVI/XVII ones).
+        if (el && c.username) el.innerHTML = `<b>${esc(c.username)}</b> / <b>${esc(c.password)}</b>`;
       }).catch(()=>{});
     }
     grid.innerHTML = html;
@@ -515,12 +528,17 @@ async function submitFlag() {
 
 async function viewCred(ch) {
   try {
-    const c = await api(`/api/credential/${ch}`);
+    const c = await api(`/api/credential/${ch}${TEAM_Q()}`);
+    // user + port both come from the server: the SSH login is per-challenge and
+    // the port is per-team, so a hardcoded table went stale for every imported
+    // challenge and for any team other than the first.
+    const user = c.username || 'ctfuser';
+    const port = c.port || 10022;
+    const host = `${ch}.attackdefense.imrnes.team`;
     document.getElementById('mcTitle').textContent = 'SSH Credentials — ' + ch;
-    const sshPort = {blogpost:10022, carbeat:11022, cdn:12022, phew:13022, sheesh:14022, warmup:15022}[ch] || 10022;
-    const cmd = `ssh ctfuser@${ch}.attackdefense.imrnes.team -p ${sshPort}`;
+    const cmd = `ssh ${user}@${host} -p ${port}`;
     document.getElementById('mcBody').innerHTML =
-      `<div>User: <b>ctfuser</b></div>
+      `<div>User: <b>${esc(user)}</b></div>
        <div>Pass: <b>${esc(c.password)}</b></div>
        <div style="margin-top:10px">SSH:</div>
        <div class="flag" style="margin-top:6px">${esc(cmd)}</div>`;
@@ -721,6 +739,87 @@ function topoReset() { topoScale = 1; topoPanX = 0; topoPanY = 0; applyTopoView(
 
 // ---------- Teams ----------
 let TEAM_LABELS = {};   // idx -> label, filled by loadTeams (for confirm dialogs)
+let TEAM_SELECTED = new Set();   // idx ticked for bulk delete
+
+function renderTeamSelectBar() {
+  const bar = document.getElementById('bulkDelBar');
+  if (!bar) return;
+  const n = TEAM_SELECTED.size;
+  if (!n) { bar.style.display = 'none'; bar.innerHTML = ''; return; }
+  const names = [...TEAM_SELECTED].sort((a, b) => a - b)
+    .map(i => `#${i} ${esc(TEAM_LABELS[i] || '')}`).join(', ');
+  bar.style.display = 'block';
+  bar.innerHTML =
+    `<div style="display:flex;align-items:center;gap:10px;flex-wrap:wrap">
+       <b style="color:#f6ad55">${n} tim dipilih</b>
+       <span style="color:#a0aec0;font-size:12px">${esc(names)}</span>
+       <button class="danger" onclick="bulkDeleteTeams()">🗑️ Hapus ${n} Tim Sekaligus</button>
+       <button onclick="clearTeamSelection()">Batalkan pilihan</button>
+     </div>`;
+}
+
+function toggleTeamSelect(idx, on) {
+  if (on) TEAM_SELECTED.add(idx); else TEAM_SELECTED.delete(idx);
+  const cb = document.getElementById(`teamSel${idx}`);
+  if (cb) cb.checked = on;
+  renderTeamSelectBar();
+}
+
+function selectAllTeams(on) {
+  TEAM_SELECTED.clear();
+  if (on) for (const k of Object.keys(TEAM_LABELS)) TEAM_SELECTED.add(Number(k));
+  for (const k of Object.keys(TEAM_LABELS)) {
+    const cb = document.getElementById(`teamSel${k}`);
+    if (cb) cb.checked = on && TEAM_SELECTED.has(Number(k));
+  }
+  renderTeamSelectBar();
+}
+
+function clearTeamSelection() { selectAllTeams(false); }
+
+async function bulkDeleteTeams() {
+  const idx = [...TEAM_SELECTED].sort((a, b) => a - b);
+  if (!idx.length) { toast('Pilih minimal satu tim dulu', true); return; }
+  const names = idx.map(i => `#${i} ${TEAM_LABELS[i] || ''}`).join(', ');
+  if (!confirm(
+    `🗑️ HAPUS ${idx.length} TIM SEKALIGUS?\n\n${names}\n\n` +
+    `Yang akan dihapus (semua tim di atas):\n` +
+    `• Semua container challenge\n• Receiver + systemd unit\n` +
+    `• Folder team (port, flag, kredensial)\n• Port firewall UFW\n` +
+    `• Domain Traefik\n• Skor & riwayat leaderboard\n\n` +
+    `⚠️ TIDAK BISA dibatalkan.`)) return;
+  showLoading(`Menghapus ${idx.length} tim (${names})…<br>Compose down 16 service per tim, bisa beberapa menit`);
+  try {
+    const d = await api('/api/teams/bulk-delete', {
+      method: 'POST', headers: {'Content-Type': 'application/json'},
+      body: JSON.stringify({indices: idx, purge_scores: true})
+    });
+    // One team takes ~100s, so poll a single job instead of blocking here.
+    const final = await pollJob(`/api/teams/bulk-delete/${d.job}`, 1500);
+    const done = final.done || [];
+    const errs = final.errors || {};
+    let msg = `Terhapus ${done.length}/${idx.length} tim`;
+    if (Object.keys(errs).length) msg += ` · gagal: ${Object.keys(errs).join(', ')}`;
+    const purged = done.reduce((a, x) =>
+      a + Object.values(x.purged || {}).reduce((p, q) => p + q, 0), 0);
+    if (purged) msg += ` · ${purged} skor dibersihkan`;
+    toast(msg, Object.keys(errs).length > 0);
+    TEAM_SELECTED.clear();
+    loadTeams();
+    if (document.getElementById('view-topo').classList.contains('active')) loadTopo();
+  } catch (e) { toast('Bulk delete gagal: ' + e.message, true); }
+  finally { hideLoading(); }
+}
+
+async function pollJob(url, everyMs) {
+  for (;;) {
+    const j = await api(url);
+    if (j.state !== 'running') return j;
+    const el = document.querySelector('#loadingText');
+    if (el && j.detail) el.innerHTML = `${esc(j.detail)}…<br><span style="font-size:11px">${esc(url.split('/').pop())}</span>`;
+    await new Promise(r => setTimeout(r, everyMs));
+  }
+}
 
 async function loadTeams() {
   try {
@@ -729,15 +828,22 @@ async function loadTeams() {
     loadLeaderboard();
     TEAM_LABELS = {};
     for (const t of d.teams) TEAM_LABELS[t.index] = t.label || ('Team ' + t.index);
+    // drop selections for teams that no longer exist
+    for (const i of [...TEAM_SELECTED]) if (!(i in TEAM_LABELS)) TEAM_SELECTED.delete(i);
     const grid = document.getElementById('teamsGrid');
-    if (!d.teams.length) { grid.innerHTML = '<div class="card"><span style="color:#718096">Belum ada team. Set jumlah team untuk auto-create.</span></div>'; return; }
+    if (!d.teams.length) { grid.innerHTML = '<div class="card"><span style="color:#718096">Belum ada team. Set jumlah team untuk auto-create.</span></div>'; renderTeamSelectBar(); return; }
     let html = '';
     for (const t of d.teams) {
       const alive = t.status === 'running';
       const dom = t.domain || '';
+      const sel = TEAM_SELECTED.has(t.index);
       html += `<div class="card ${alive ? '' : 'dead'}">
         <div class="team-head">
-          <span class="ch-name">${esc(t.label || ('Team ' + t.index))}</span>
+          <label style="display:flex;align-items:center;gap:6px;cursor:pointer;user-select:none" title="Pilih untuk hapus massal">
+            <input type="checkbox" id="teamSel${t.index}" ${sel ? 'checked' : ''}
+                   onchange="toggleTeamSelect(${t.index}, this.checked)">
+            <span class="ch-name">${esc(t.label || ('Team ' + t.index))}</span>
+          </label>
           <span class="status ${alive ? 'up' : 'down'}">${alive ? '● RUNNING' : '● STOPPED'}</span>
         </div>
         <div class="kv">
@@ -758,6 +864,7 @@ async function loadTeams() {
       </div>`;
     }
     grid.innerHTML = html;
+    renderTeamSelectBar();
   } catch (e) { toast('Teams gagal: ' + e.message, true); }
 }