feat(ui): watchlist empty-state + chat error styling + hint

- WatchlistDrawer: shows helpful hint ('Ketik kode saham lalu Add') when empty
- ChatSidebar: errors in text-destructive, empty state explains how chat works
- styled-components/timestamp formatting and company-name display already in previous commit

web/src/components/WatchlistChat.tsx

@@ -36,7 +36,9 @@ export function WatchlistDrawer() {
         </div>
         <Show when={err()}><p class="text-xs text-destructive">{err()}</p></Show>
         <ul class="flex flex-wrap gap-1.5">
-          <For each={wl()?.watchlist || []}>{(t) => <li class="flex items-center gap-1"><a href={`/report/${encodeURIComponent(t)}`}><Badge variant="secondary">{t}</Badge></a> <button class="text-xs text-muted-foreground hover:text-foreground" aria-label={`Hapus ${t} dari watchlist`} onClick={() => del(t)}>×</button></li>}</For>
+          <Show when={(wl()?.watchlist || []).length} fallback={<li class="text-xs text-muted-foreground">Ketik kode saham lalu Add — mis. BBCA, TLKM, BBRI.</li>}>
+            <For each={wl()?.watchlist || []}>{(t) => <li class="flex items-center gap-1"><a href={`/report/${encodeURIComponent(t)}`}><Badge variant="secondary">{t}</Badge></a> <button class="text-xs text-muted-foreground hover:text-foreground" aria-label={`Hapus ${t} dari watchlist`} onClick={() => del(t)}>×</button></li>}</For>
+          </Show>
         </ul>
       </CardContent>
     </Card>
@@ -45,7 +47,7 @@ export function WatchlistDrawer() {
 
 export function ChatSidebar() {
   const [msg, setMsg] = createSignal("");
-  const [log, setLog] = createSignal<{ q: string; a: string }[]>([]);
+  const [log, setLog] = createSignal<{ q: string; a: string; err?: boolean }[]>([]);
   async function send() {
     const q = msg().trim();
     if (!q) return;
@@ -54,18 +56,25 @@ export function ChatSidebar() {
       const r = await api.chat(q);
       setLog((p) => [...p, { q, a: r.answer }].slice(-10));
     } catch (e) {
-      setLog((p) => [...p, { q, a: String(e) }].slice(-10));
+      setLog((p) => [...p, { q, a: String(e), err: true }].slice(-10));
     }
   }
   return (
     <Card>
       <CardHeader class="pb-2"><CardTitle class="text-base">AI Chat</CardTitle></CardHeader>
       <CardContent class="space-y-2">
-        <div class="max-h-64 space-y-2 overflow-y-auto">
+        <Show when={log().length} fallback={<p class="text-xs text-muted-foreground">Tanya soal watchlist-mu — sistem jawab dari data yang tersimpan (bukan karangan).</p>}>
-          <For each={log()}>
+          <div class="max-h-64 space-y-2 overflow-y-auto">
-            {(m) => <div class="text-sm"><p><strong>You:</strong> {m.q}</p><p class="text-muted-foreground">{m.a.slice(0, 500)}</p></div>}
+            <For each={log()}>
-          </For>
+              {(m) => (
-        </div>
+                <div class="text-sm">
+                  <p><strong>You:</strong> {m.q}</p>
+                  <p classList={{ "text-muted-foreground": !m.err, "text-destructive": !!m.err }}>{m.a.slice(0, 500)}</p>
+                </div>
+              )}
+            </For>
+          </div>
+        </Show>
         <div class="flex gap-2">
           <label class="sr-only" for="chat-msg">Tanya AI</label>
           <TextField class="flex-1"><TextFieldInput id="chat-msg" placeholder="Ask about your watchlist…" value={msg()} onInput={(e) => setMsg(e.currentTarget.value)} onKeyDown={(e: KeyboardEvent) => { if (e.key === "Enter") send(); }} /></TextField>