Multi-user sharing, groups, and in-app notifications

Backend:
- Alembic migration 0025: groups, group_memberships, project_shares,
  note_shares, notifications tables
- models: Group, GroupMembership, ProjectShare, NoteShare, Notification
- services/access.py: permission resolution (viewer/editor/admin/owner)
- services/groups.py + routes/groups.py: full group CRUD + membership
- services/sharing.py + routes/shares.py: project/note sharing API
- services/notifications.py: in-app notification create/list/mark-read
- routes/in_app_notifications.py: GET/POST notification endpoints
- routes/users.py: user search endpoint
- services/projects.py + services/notes.py: *_for_user variants
- routes updated to use *_for_user on get/list; adds permission field
- app.py: register all new blueprints

Frontend:
- api/client.ts: ShareEntry, GroupEntry, NotificationEntry types + helpers
- stores/notifications.ts: Pinia store with polling
- NotificationBell.vue: bell icon + badge + dropdown toggle + 60s poll
- NotificationsPanel.vue: unread notification list with mark-all-read
- ShareDialog.vue: teleport modal for sharing projects/notes with users/groups
- SharedWithMeView.vue: /shared route listing shared projects and notes
- AppHeader: NotificationBell, Shared nav link
- ProjectView, NoteViewerView, TaskViewerView: Share button + ShareDialog
- SettingsView: Groups admin tab with create/delete groups + member mgmt
- router: /shared route

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

frontend/src/api/client.ts

@@ -75,6 +75,111 @@ export async function apiDelete(path: string): Promise<void> {
   return handleResponse<void>(res, path);
 }
 
+// ---------------------------------------------------------------------------
+// Sharing, Groups, Notifications, User search
+// ---------------------------------------------------------------------------
+
+export interface ShareEntry {
+  id: number
+  permission: string
+  shared_with_user_id: number | null
+  shared_with_group_id: number | null
+  username?: string
+  group_name?: string
+  invited_by: number
+  created_at: string
+}
+
+export interface GroupEntry {
+  id: number
+  name: string
+  description: string | null
+  created_by: number | null
+  member_count: number
+  is_member: boolean
+  created_at: string
+  updated_at: string
+}
+
+export interface GroupMember {
+  id: number
+  group_id: number
+  user_id: number
+  role: string
+  username: string
+  email: string | null
+  created_at: string
+}
+
+export interface NotificationEntry {
+  id: number
+  user_id: number
+  type: string
+  payload: Record<string, unknown>
+  read_at: string | null
+  created_at: string
+}
+
+export interface UserSearchResult {
+  id: number
+  username: string
+  email: string | null
+}
+
+// --- User search ---
+export const searchUsers = (q: string) =>
+  apiGet<{ users: UserSearchResult[] }>(`/api/users/search?q=${encodeURIComponent(q)}`).then(r => r.users)
+
+// --- Groups ---
+export const listGroups = () => apiGet<{ groups: GroupEntry[] }>('/api/groups').then(r => r.groups)
+export const createGroup = (name: string, description?: string) =>
+  apiPost<GroupEntry>('/api/groups', { name, description })
+export const updateGroup = (id: number, data: { name?: string; description?: string }) =>
+  apiPatch<GroupEntry>(`/api/groups/${id}`, data)
+export const deleteGroup = (id: number) => apiDelete(`/api/groups/${id}`)
+export const getGroupDetail = (id: number) =>
+  apiGet<GroupEntry & { members: GroupMember[] }>(`/api/groups/${id}`)
+export const listGroupMembers = (id: number) =>
+  apiGet<{ members: GroupMember[] }>(`/api/groups/${id}/members`).then(r => r.members)
+export const addGroupMember = (groupId: number, userId: number, role: string) =>
+  apiPost<GroupMember>(`/api/groups/${groupId}/members`, { user_id: userId, role })
+export const updateGroupMember = (groupId: number, userId: number, role: string) =>
+  apiPatch<GroupMember>(`/api/groups/${groupId}/members/${userId}`, { role })
+export const removeGroupMember = (groupId: number, userId: number) =>
+  apiDelete(`/api/groups/${groupId}/members/${userId}`)
+
+// --- Project shares ---
+export const listProjectShares = (projectId: number) =>
+  apiGet<{ shares: ShareEntry[] }>(`/api/projects/${projectId}/shares`).then(r => r.shares)
+export const createProjectShare = (projectId: number, body: { user_id?: number; group_id?: number; permission: string }) =>
+  apiPost<ShareEntry>(`/api/projects/${projectId}/shares`, body)
+export const updateProjectShare = (projectId: number, shareId: number, permission: string) =>
+  apiPatch<ShareEntry>(`/api/projects/${projectId}/shares/${shareId}`, { permission })
+export const deleteProjectShare = (projectId: number, shareId: number) =>
+  apiDelete(`/api/projects/${projectId}/shares/${shareId}`)
+
+// --- Note / task shares ---
+export const listNoteShares = (noteId: number) =>
+  apiGet<{ shares: ShareEntry[] }>(`/api/notes/${noteId}/shares`).then(r => r.shares)
+export const createNoteShare = (noteId: number, body: { user_id?: number; group_id?: number; permission: string }) =>
+  apiPost<ShareEntry>(`/api/notes/${noteId}/shares`, body)
+export const updateNoteShare = (noteId: number, shareId: number, permission: string) =>
+  apiPatch<ShareEntry>(`/api/notes/${noteId}/shares/${shareId}`, { permission })
+export const deleteNoteShare = (noteId: number, shareId: number) =>
+  apiDelete(`/api/notes/${noteId}/shares/${shareId}`)
+
+// --- Shared-with-me ---
+export const getSharedWithMe = () =>
+  apiGet<{ projects: Record<string, unknown>[]; notes: Record<string, unknown>[] }>('/api/shared-with-me')
+
+// --- In-app notifications ---
+export const getNotifications = (all = false) =>
+  apiGet<{ notifications: NotificationEntry[] }>(`/api/notifications${all ? '?all=true' : ''}`).then(r => r.notifications)
+export const getNotificationCount = () =>
+  apiGet<{ count: number }>('/api/notifications/count').then(r => r.count)
+export const markNotificationRead = (id: number) => apiPost<void>(`/api/notifications/${id}/read`, {})
+export const markAllNotificationsRead = () => apiPost<{ marked: number }>('/api/notifications/read-all', {})
+
 export interface SSEStreamHandle {
   close(): void;
   /** Resolves when the stream closes (normally or via error/abort). */