feat(p10): archivage automatique des sessions terminées (rétention configurable)

- DB: migration #10 (sessions.archived_at + index), helpers archive/unarchive/archiveExpired (soft-archive, jamais de DELETE)
- core/retention-settings.ts: session_retention_days (défaut 30, 0=jamais, 1-3650) + session_purge_days (off)
- core/session-archive.ts: scheduler start/stop/sweep (calqué DiscoveryService), câblé dans runDaemon
- pty-manager.list({includeArchived}) + SessionSummary.archived + emitHistoricalUpdate
- routes: GET /sessions?includeArchived, POST/DELETE /sessions/:id/archive, POST /sessions/archive-now
- protocole additif: message WS session_archived (relayé par la gateway, abonnés 'sessions')
- settings: retentionDays/purgeDays exposés et validés dans PATCH /settings
- web: store sessions (showArchived + archive/unarchive), SessionsListView (toggle/badge/actions), SettingsView (slider rétention), i18n EN+FR
- tests: retention-settings + session-archive (vitest) + settings-routes étendu ; acceptance-p10.mjs (sweep, event WS, resume d'une session archivée → 201, rétention=0)

packages/web/src/stores/settings.ts

@@ -11,6 +11,8 @@ export const useSettingsStore = defineStore('settings', () => {
   const scanIntervalMin = ref(0);
   const claudeBinPath = ref<string | null>(null);
   const claudeHome = ref<string | null>(null);
+  const retentionDays = ref(0);
+  const purgeDays = ref(0);
   const loaded = ref(false);
   const saving = ref(false);
 
@@ -20,6 +22,8 @@ export const useSettingsStore = defineStore('settings', () => {
     scanIntervalMin.value = res.settings.scanIntervalMin;
     claudeBinPath.value = res.settings.claudeBinPath;
     claudeHome.value = res.settings.claudeHome;
+    retentionDays.value = res.settings.retentionDays;
+    purgeDays.value = res.settings.purgeDays;
     loaded.value = true;
   }
 
@@ -36,5 +40,5 @@ export const useSettingsStore = defineStore('settings', () => {
     }
   }
 
-  return { server, scanRoots, scanIntervalMin, claudeBinPath, claudeHome, loaded, saving, fetch, save };
+  return { server, scanRoots, scanIntervalMin, claudeBinPath, claudeHome, retentionDays, purgeDays, loaded, saving, fetch, save };
 });