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/uiPreferences.ts

@@ -0,0 +1,65 @@
+/**
+ * `localStorage`-backed {@link UiPreferencesGateway} (ticket #29).
+ *
+ * The only place that touches `window.localStorage`; features go through the
+ * port via DI. Everything is best-effort: a missing / private-mode / quota-full
+ * storage, or a corrupt JSON entry, degrades silently to "no preference" rather
+ * than throwing into the UI (persisted UI filters must never break the app).
+ */
+
+import type { UiPreferencesGateway } from "@/ports";
+
+/** Returns the `Storage` if usable in this environment, else `null`. */
+function storage(): Storage | null {
+  try {
+    return typeof window !== "undefined" ? window.localStorage : null;
+  } catch {
+    // Accessing `localStorage` can throw (sandboxed / disabled cookies).
+    return null;
+  }
+}
+
+export class LocalStorageUiPreferencesGateway implements UiPreferencesGateway {
+  read(key: string): unknown {
+    const store = storage();
+    if (!store) return null;
+    let raw: string | null;
+    try {
+      raw = store.getItem(key);
+    } catch {
+      return null;
+    }
+    if (raw === null) return null;
+    try {
+      return JSON.parse(raw);
+    } catch {
+      // Corrupt entry — drop it so we stop tripping over it, return default.
+      try {
+        store.removeItem(key);
+      } catch {
+        /* ignore */
+      }
+      return null;
+    }
+  }
+
+  write(key: string, value: unknown): void {
+    const store = storage();
+    if (!store) return;
+    try {
+      store.setItem(key, JSON.stringify(value));
+    } catch {
+      /* quota / serialisation failure — persistence is best-effort */
+    }
+  }
+
+  remove(key: string): void {
+    const store = storage();
+    if (!store) return;
+    try {
+      store.removeItem(key);
+    } catch {
+      /* ignore */
+    }
+  }
+}