feat(p11): temps réel complet (watcher checkout principal + topic settings)

P11-A — branche du checkout principal modifiée hors Arboretum :
- fs-watcher: pin « permanent » non évinçable (pinRepo/unpinRepo, repoPins dans evictIfNeeded)
- worktree-manager: armMainCheckoutWatchers() + arm/désarm sur addRepo/découverte/removeRepo/hidden
- index.ts: armMainCheckoutWatchers() dans runDaemon → git checkout CLI sur le principal → worktree_update <500ms sans watch client

P11-B — réglages en temps réel :
- protocole additif: type SettingsBroadcast (source unique, réutilisé par SettingsResponse), topic 'settings', message settings_update (validés parseClientMessage + gateway)
- core/settings-bus.ts (EventEmitter) ; routes/settings émet après PATCH ; gateway relaie aux abonnés 'settings'
- web: ws-client subscribeSettings + routage ; store settings applySettings/startRealtime ; AppShell abonne globalement ; SettingsView re-sync des drafts scalaires sans écraser une saisie en cours
- tests: protocol (topic settings) + fs-watcher (pinRepo non évincé) ; acceptance-p11.mjs (checkout principal <500ms + settings_update)

packages/shared/test/protocol.test.ts

@@ -62,7 +62,7 @@ function assertInvariants(msg: ClientMessage): void {
       expect(msg.bytes).toBeGreaterThanOrEqual(0);
       break;
     case 'sub':
-      expect(msg.topics.every((t) => t === 'sessions' || t === 'worktrees' || t === 'groups')).toBe(true);
+      expect(msg.topics.every((t) => t === 'sessions' || t === 'worktrees' || t === 'groups' || t === 'settings')).toBe(true);
       break;
     case 'ping':
       break;
@@ -128,6 +128,12 @@ describe('parseClientMessage — cas valides', () => {
     expect(parseClientMessage('{"type":"sub","topics":[]}')).toEqual({ type: 'sub', topics: [] });
   });
 
+  it('sub accepte le topic settings (P11) et rejette un topic inconnu', () => {
+    expect(parseClientMessage('{"type":"sub","topics":["settings"]}')).toEqual({ type: 'sub', topics: ['settings'] });
+    expect(parseClientMessage('{"type":"sub","topics":["sessions","settings"]}')).toEqual({ type: 'sub', topics: ['sessions', 'settings'] });
+    expect(parseClientMessage('{"type":"sub","topics":["bogus"]}')).toBeNull();
+  });
+
   it('watch / unwatch (P7) avec repoId + path', () => {
     expect(parseClientMessage('{"type":"watch","repoId":"r1","path":"/home/u/wt"}')).toEqual({ type: 'watch', repoId: 'r1', path: '/home/u/wt' });
     expect(parseClientMessage('{"type":"unwatch","repoId":"r1","path":"/home/u/wt"}')).toEqual({ type: 'unwatch', repoId: 'r1', path: '/home/u/wt' });