fix(frontend): mobile navbar navigation + SSR hydration mismatch

Root cause of 'navbar mobile tak bisa pindah halaman': Next <Link>
client-side navigation is dead app-wide. A React hydration mismatch
(#418: 'server rendered text didn't match the client') is thrown by the
SSR-seeded live feeds — relative times (formatRelativeTime(e.edited_at) /
m.created_at) computed with Date.now() render slightly differently on
server vs client, which breaks the Next client router (router.push is a
no-op). The desktop NavRail worked only because it uses plain <a href>
(hard navigation bypasses the broken router).

Fixes:
- mobile-nav.tsx: use plain <a href> (NOT Next <Link>), identical to the
  working sidebar NavRail, so mobile nav always navigates regardless of
  router state ('ikuti cara kerja sidebar').
- Add suppressHydrationWarning to the SSR-seeded relative-time spans so
  server/client drift no longer throws #418 (EditHistory, LiveModerationFeed,
  messages/results + detail rows, recordings, TermGlossary,
  ChannelCultureGlossary, CategoryDrilldown).

Verified on non-prod :4024 @375px: Voice/Media/Search all navigate, no #418
in console. Plan: .hermes/plans/mobile-nav-hydration-fix.md

services/frontend/AGENTS.md

@@ -51,3 +51,13 @@ Discord → discord-gateway → Redis pub/sub → backend (Express :4001) ←→
   not top-level.
 - `GET /api/voice/status` now includes `activeSpeakers` (authoritative shared
   snapshot from `src/modules/voice/live-speaker.ts` on the backend).
+
+<!-- BEGIN:nextjs-agent-rules -->
+
+# This is NOT the Next.js you know
+
+This version has breaking changes — APIs, conventions, and file structure may all differ from your training data. Read the relevant guide in `node_modules/next/dist/docs/` (resolved from this file's directory; in monorepos the `next` package may not be visible from the repo root) before writing any code. Heed deprecation notices.
+
+This block is written and re-added by `next dev` — verify at `node_modules/next/dist/server/lib/generate-agent-files.js`. Removing it from a diff only re-creates the uncommitted change; committing it with your work keeps the tree clean.
+
+<!-- END:nextjs-agent-rules -->