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/server/src/routes/settings.ts

@@ -24,6 +24,14 @@ import {
   readClaudeBinPath,
   readClaudeHome,
 } from '../core/claude-settings.js';
+import {
+  PURGE_DAYS_KEY,
+  RETENTION_DAYS_KEY,
+  normalizePurgeDays,
+  normalizeRetentionDays,
+  readPurgeDays,
+  readRetentionDays,
+} from '../core/retention-settings.js';
 
 // Réglages modifiables via l'API (allow-list stricte). Les secrets ne figurent JAMAIS ici.
 export function registerSettingsRoutes(
@@ -51,6 +59,8 @@ export function registerSettingsRoutes(
       scanIntervalMin: readScanIntervalMin(db),
       claudeBinPath: readClaudeBinPath(db),
       claudeHome: readClaudeHome(db),
+      retentionDays: readRetentionDays(db),
+      purgeDays: readPurgeDays(db),
     },
     server: serverInfo(),
   });
@@ -87,6 +97,20 @@ export function registerSettingsRoutes(
       }
       setSetting(db, CLAUDE_HOME_KEY, value);
     }
+    if ('retentionDays' in body) {
+      const value = normalizeRetentionDays(body.retentionDays);
+      if (value === null) {
+        return reply.status(400).send({ error: { code: 'BAD_REQUEST', message: 'retentionDays must be 0 (never) or an integer between 1 and 3650' } });
+      }
+      setSetting(db, RETENTION_DAYS_KEY, String(value));
+    }
+    if ('purgeDays' in body) {
+      const value = normalizePurgeDays(body.purgeDays);
+      if (value === null) {
+        return reply.status(400).send({ error: { code: 'BAD_REQUEST', message: 'purgeDays must be 0 (disabled) or an integer between 1 and 3650' } });
+      }
+      setSetting(db, PURGE_DAYS_KEY, String(value));
+    }
     recordAudit(db, {
       actor: req.authContext?.tokenId ?? 'unknown',
       action: 'settings.update',