feat(tickets): persistance des filtres tickets entre redémarrages (#29)

Introduit le port UiPreferencesGateway et son adapter uiPreferences,
avec le module ticketFilterPersistence qui sauvegarde/restaure les
filtres (recherche, statut, sprint, agents) via useTickets,
useTicketSearch et useProjectAgents. Couvert par tests unitaires et
un test d'intégration.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

frontend/src/adapters/mock/index.ts

@@ -88,6 +88,7 @@ import type {
   TicketListQuery,
   CreateTicketInput,
   UpdateTicketInput,
+  UiPreferencesGateway,
   ViewWindowClosed,
   WindowGateway,
   WorkStateGateway,
@@ -2529,6 +2530,38 @@ export class MockTicketGateway implements TicketGateway {
   }
 }
 
+/**
+ * In-memory {@link UiPreferencesGateway} for tests/dev (ticket #29). Mirrors the
+ * localStorage adapter's best-effort JSON round-trip without touching the DOM,
+ * so persisted-filter behaviour can be exercised offline.
+ */
+export class MockUiPreferencesGateway implements UiPreferencesGateway {
+  private readonly store = new Map<string, string>();
+
+  read(key: string): unknown {
+    const raw = this.store.get(key);
+    if (raw === undefined) return null;
+    try {
+      return JSON.parse(raw);
+    } catch {
+      this.store.delete(key);
+      return null;
+    }
+  }
+
+  write(key: string, value: unknown): void {
+    try {
+      this.store.set(key, JSON.stringify(value));
+    } catch {
+      /* best-effort */
+    }
+  }
+
+  remove(key: string): void {
+    this.store.delete(key);
+  }
+}
+
 function mostRestrictive(
   project?: PermissionSet["fallback"],
   agent?: PermissionSet["fallback"],
@@ -2563,6 +2596,7 @@ export function createMockGateways(): Gateways {
     conversation: new MockConversationGateway(),
     ticket: new MockTicketGateway(systemGateway),
     window: new MockWindowGateway(),
+    uiPreferences: new MockUiPreferencesGateway(),
   };
 }