transmission, extracted into plugins/transmission — the platform half

Sixth extraction, straight after photos. Everything transmission now lives at
gitea.officer.dev/plugins/transmission.

Deleted, not commented: the sidecar, the api router, the Transmission app (28
files including detail/ and dialogs/), the screen, the App.tsx route pair, the
Dashboard barrel line, the usePageTitle rule, the AppRegistry wiring, the
officerdev barrel re-exports, the permission registry entry, the hono.ts import
and mount comments, and the app-store catalogue entry.

No database change: transmission owns no tables. Its connection lives in
service_connections, a core table it now depends on from outside — a real
coupling, recorded in the plugin's own PLUGIN.md rather than left to be
discovered.

── Test fixtures, repointed rather than deleted ──

Transmission was the canonical `members: 'none'` fixture — a single-tenant
daemon with no user concept — across three app-store test files. slskd has the
identical shape, so the assertions moved there. Deleting them would have
quietly dropped coverage of the no-members install path along with the plugin,
which is the same trap the vault extraction hit with `members: 'invite'`.

── Vocabulary swept, per the runbook ──

Six screens and two App.tsx comments pointed at `/photos` or `/transmission` as
the worked example of the Workspace/Panel shape. Both are plugins now, so those
pointers dangled at code no longer in the tree. Repointed at /command-hq and
/soulseek, which are core.

bunx tsgo clean. 1080 pass / 0 fail.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

src/apps/officer-web/state/usePageTitle.ts

@@ -26,7 +26,6 @@ const RULES: TitleRule[] = [
   { match: (p) => p.startsWith('/jellyfin'), title: 'Video' },
   { match: (p) => p.startsWith('/soulseek'), title: 'Soulseek' },
   { match: (p) => p.startsWith('/command-hq'), title: 'Command HQ' },
-  { match: (p) => p.startsWith('/transmission'), title: 'Transmission' },
   { match: (p) => p.startsWith('/gitea'), title: 'Gitea' },
   { match: (p) => p.startsWith('/invoices'), title: 'Invoices' },
   { match: (p) => p.startsWith('/wallet'), title: 'Wallet' },