feat(web): complete du-an project pages, neighborhood components, and public notification bell

- Add grid/map view toggle on /du-an listing page with Mapbox project markers
- Enhance du-an detail with master plan viewer, neighborhood radar chart, POI map, and price history chart
- Create neighborhood component suite: radar chart (Recharts), POI map (Mapbox), score badges
- Add du-an API client, server-side fetching, and React Query hooks
- Wire NotificationBell into public layout header for authenticated users
- Fix missing PROJECT_STATUS_COLORS import in du-an detail client

Co-Authored-By: Paperclip <noreply@paperclip.ing>

apps/web/lib/du-an-server.ts

@@ -0,0 +1,58 @@
+/**
+ * Server-side project data fetching for Next.js Server Components.
+ *
+ * Uses `fetch` directly (no browser-only helpers) so it can run
+ * inside `generateMetadata`, `generateStaticParams`, `sitemap()`, etc.
+ */
+
+import type { ProjectDetail, ProjectSummary, PaginatedResult } from './du-an-api';
+
+const API_BASE_URL = process.env['NEXT_PUBLIC_API_URL'] || 'http://localhost:3001/api/v1';
+
+/**
+ * Fetch a single project by slug — server-only.
+ * Returns `null` when the project is not found (404) so callers can `notFound()`.
+ */
+export async function fetchProjectBySlug(slug: string): Promise<ProjectDetail | null> {
+  try {
+    const res = await fetch(`${API_BASE_URL}/projects/${slug}`, {
+      next: { revalidate: 300 }, // ISR: re-validate every 5 min
+    });
+
+    if (!res.ok) return null;
+    return (await res.json()) as ProjectDetail;
+  } catch {
+    return null;
+  }
+}
+
+/**
+ * Fetch active projects — server-only, used by the dynamic sitemap.
+ */
+export async function fetchProjects(params: {
+  page?: number;
+  limit?: number;
+  city?: string;
+  status?: string;
+}): Promise<PaginatedResult<ProjectSummary>> {
+  const query = new URLSearchParams({
+    page: String(params.page ?? 1),
+    limit: String(params.limit ?? 100),
+  });
+  if (params.city) query.append('city', params.city);
+  if (params.status) query.append('status', params.status);
+
+  try {
+    const res = await fetch(`${API_BASE_URL}/projects?${query}`, {
+      next: { revalidate: 3600 }, // re-validate every hour for sitemap
+    });
+
+    if (!res.ok) {
+      return { data: [], total: 0, page: 1, limit: 100, totalPages: 0 };
+    }
+
+    return (await res.json()) as PaginatedResult<ProjectSummary>;
+  } catch {
+    return { data: [], total: 0, page: 1, limit: 100, totalPages: 0 };
+  }
+}