feat: add notifications and project shares features

- Backend: notifications + shares routes, DB tables, SqliteAdapter methods
- Frontend: NotificationPanel (bell icon + dropdown), ShareDialog, Dashboard integration
- Styles: notification + share dialog CSS

frontend/src/services/api.ts

@@ -387,6 +387,81 @@ export async function loadProjectDataTyped(token: string, projectId: string): Pr
   return promise;
 }
 
+// ─── Notifications ───────────────────────────────────────
+export interface NotificationItem {
+  id: string;
+  user_id: string;
+  type: string;
+  title: string;
+  message: string;
+  read: number;
+  created_at: string;
+}
+
+export async function getNotifications(token: string): Promise<NotificationItem[]> {
+  const res = await fetch(`${API_BASE}/api/notifications`, { headers: authHeaders(token) });
+  if (!res.ok) throw new Error('Failed to load notifications');
+  return res.json();
+}
+
+export async function createNotification(token: string, data: { type?: string; title: string; message: string; user_id?: string }): Promise<NotificationItem> {
+  const res = await fetch(`${API_BASE}/api/notifications`, {
+    method: 'POST',
+    headers: authHeaders(token),
+    body: JSON.stringify(data),
+  });
+  if (!res.ok) throw new Error('Failed to create notification');
+  return res.json();
+}
+
+export async function markNotificationRead(token: string, id: string): Promise<void> {
+  await fetch(`${API_BASE}/api/notifications/${id}/read`, {
+    method: 'PATCH',
+    headers: authHeaders(token),
+  });
+}
+
+export async function deleteNotification(token: string, id: string): Promise<void> {
+  await fetch(`${API_BASE}/api/notifications/${id}`, {
+    method: 'DELETE',
+    headers: authHeaders(token),
+  });
+}
+
+// ─── Project Shares ──────────────────────────────────────
+export interface ProjectShare {
+  id: string;
+  project_id: string;
+  shared_with_email: string;
+  shared_by: string;
+  permission: string;
+  share_token: string | null;
+  created_at: string;
+}
+
+export async function getProjectShares(token: string, projectId: string): Promise<ProjectShare[]> {
+  const res = await fetch(`${API_BASE}/api/projects/${projectId}/shares`, { headers: authHeaders(token) });
+  if (!res.ok) throw new Error('Failed to load shares');
+  return res.json();
+}
+
+export async function createProjectShare(token: string, projectId: string, data: { shared_with_email: string; permission?: string }): Promise<ProjectShare> {
+  const res = await fetch(`${API_BASE}/api/projects/${projectId}/shares`, {
+    method: 'POST',
+    headers: authHeaders(token),
+    body: JSON.stringify(data),
+  });
+  if (!res.ok) throw new Error('Failed to create share');
+  return res.json();
+}
+
+export async function deleteProjectShare(token: string, shareId: string): Promise<void> {
+  await fetch(`${API_BASE}/api/shares/${shareId}`, {
+    method: 'DELETE',
+    headers: authHeaders(token),
+  });
+}
+
 export { API_BASE };
 
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