feat: county sync on monitor page + in-app notification system

- GET /api/eterra/counties — distinct county list from GisUat
- POST /api/eterra/sync-county — background sync all UATs in a county
  (TERENURI + CLADIRI + INTRAVILAN), magic mode for enriched UATs,
  concurrency guard, creates notification on completion
- In-app notification service (KeyValueStore, CRUD, unread count)
- GET/PATCH /api/notifications/app — list and mark-read endpoints
- NotificationBell component in header with popover + polling
- Monitor page: county select dropdown + SyncTestButton with customBody

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

src/app/api/notifications/app/route.ts

@@ -0,0 +1,56 @@
+/**
+ * GET  /api/notifications/app          — list recent + unread count
+ * PATCH /api/notifications/app         — mark read / mark all read
+ *
+ * Body for PATCH:
+ *   { action: "mark-read", id: string }
+ *   { action: "mark-all-read" }
+ */
+import { NextResponse } from "next/server";
+import {
+  getAppNotifications,
+  getUnreadCount,
+  markAsRead,
+  markAllAsRead,
+} from "@/core/notifications/app-notifications";
+
+export const runtime = "nodejs";
+export const dynamic = "force-dynamic";
+
+export async function GET(req: Request) {
+  try {
+    const url = new URL(req.url);
+    const limit = Math.min(parseInt(url.searchParams.get("limit") ?? "30", 10), 100);
+
+    const [notifications, unreadCount] = await Promise.all([
+      getAppNotifications(limit),
+      getUnreadCount(),
+    ]);
+
+    return NextResponse.json({ notifications, unreadCount });
+  } catch (error) {
+    const msg = error instanceof Error ? error.message : "Eroare notificari";
+    return NextResponse.json({ error: msg }, { status: 500 });
+  }
+}
+
+export async function PATCH(req: Request) {
+  try {
+    const body = (await req.json()) as { action: string; id?: string };
+
+    if (body.action === "mark-read" && body.id) {
+      await markAsRead(body.id);
+      return NextResponse.json({ ok: true });
+    }
+
+    if (body.action === "mark-all-read") {
+      await markAllAsRead();
+      return NextResponse.json({ ok: true });
+    }
+
+    return NextResponse.json({ error: "Actiune necunoscuta" }, { status: 400 });
+  } catch (error) {
+    const msg = error instanceof Error ? error.message : "Eroare notificari";
+    return NextResponse.json({ error: msg }, { status: 500 });
+  }
+}