P3-C: dashboard worktree-first + acceptance P3 (MVP complet)

Vue racine consolidée : repos → worktrees avec état git ET état de session
corrélé. Complète le MVP (P2 découverte/reprise + P3-A worktrees + P3-B états fins).

- web/lib/ws-client: abonnement multi-topics (sessions + worktrees), subscribeWorktrees.
- web/stores/worktrees: repos + worktrees, CRUD, temps réel (repo_update/worktree_*).
- web/views/DashboardView (route racine /), components RepoSection + WorktreeCard ;
  SessionStateBadge réutilisé pour l'état des sessions corrélées.
- router: / = dashboard, /sessions = liste à plat (sessions hors worktree), nav croisée.
- i18n EN/FR (dashboard/repos/worktrees).
- fix: @xterm/headless est CommonJS → chargé via createRequire (l'import nommé ESM
  échouait sous Node natif, masqué par esbuild en test) ; détecté par l'acceptation.
- scripts/acceptance-p3.mjs: repo git tmp → enregistrement, worktree + hook, broadcast
  WS worktree_update, corrélation session bash, suppression (409 sans force, 200 avec).

Vérifs : typecheck, 159 tests, build (vue-tsc), acceptations P1/P2/P3 ALL GREEN.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

packages/web/src/i18n/en.ts

@@ -48,6 +48,39 @@ export default {
       waiting: 'waiting',
     },
   },
+  dashboard: {
+    title: 'Worktrees',
+    allSessions: 'All sessions',
+  },
+  repos: {
+    add: 'Add repo',
+    adding: 'Adding…',
+    remove: 'Remove',
+    pathLabel: 'Repository path',
+    pathPlaceholder: '/absolute/path/to/repo',
+    empty: 'No repository registered yet — add one above.',
+    invalid: 'unavailable',
+  },
+  worktrees: {
+    new: 'New worktree',
+    create: 'Create',
+    creating: 'Creating…',
+    branch: 'Branch',
+    newBranch: 'create branch',
+    start: 'Start',
+    startNone: 'no session',
+    delete: 'Delete',
+    confirmDelete: 'Confirm delete',
+    forceDelete: 'Force delete',
+    prune: 'Prune',
+    main: 'main',
+    detached: 'detached',
+    locked: 'locked',
+    prunable: 'prunable',
+    clean: 'clean',
+    dirty: '{n} changed',
+    noSession: 'no session',
+  },
   terminal: {
     observer: 'observer (read-only)',
     sessionEnded: 'Session ended',