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>

src/fabledassistant/services/projects.py

@@ -144,3 +144,78 @@ async def get_project_summary(user_id: int, project_id: int) -> dict:
             "last_activity": last_activity_result.isoformat() if last_activity_result else None,
             "milestone_summary": milestone_summary,
         }
+
+
+# ---------------------------------------------------------------------------
+# Shared-access variants (honour ProjectShare in addition to ownership)
+# ---------------------------------------------------------------------------
+
+async def get_project_for_user(
+    accessing_user_id: int, project_id: int
+) -> tuple[Project, str] | None:
+    """Returns (project, permission) if user has any access, else None."""
+    from fabledassistant.services.access import get_project_permission
+    perm = await get_project_permission(accessing_user_id, project_id)
+    if perm is None:
+        return None
+    async with async_session() as session:
+        project = await session.get(Project, project_id)
+    return (project, perm) if project else None
+
+
+async def list_projects_for_user(user_id: int, status: str | None = None) -> list[dict]:
+    """Owned projects + shared projects, each dict has 'permission' field."""
+    from fabledassistant.models.group import GroupMembership
+    from fabledassistant.models.share import ProjectShare
+    from fabledassistant.services.access import PERMISSION_RANK
+
+    owned = await list_projects(user_id, status)
+    owned_ids = {p.id for p in owned}
+
+    result = []
+    for p in owned:
+        d = p.to_dict() if hasattr(p, "to_dict") else {"id": p.id, "title": p.title}
+        d["permission"] = "owner"
+        result.append(d)
+
+    async with async_session() as session:
+        user_group_ids = (await session.execute(
+            select(GroupMembership.group_id).where(GroupMembership.user_id == user_id)
+        )).scalars().all()
+
+        shared_direct = (await session.execute(
+            select(ProjectShare).where(ProjectShare.shared_with_user_id == user_id)
+        )).scalars().all()
+
+        shared_group: list[ProjectShare] = []
+        if user_group_ids:
+            shared_group = (await session.execute(
+                select(ProjectShare).where(
+                    ProjectShare.shared_with_group_id.in_(user_group_ids)
+                )
+            )).scalars().all()
+
+    seen: dict[int, str] = {}
+    for share in list(shared_direct) + list(shared_group):
+        if share.project_id in owned_ids:
+            continue
+        prev = seen.get(share.project_id)
+        if prev is None or PERMISSION_RANK[share.permission] > PERMISSION_RANK[prev]:
+            seen[share.project_id] = share.permission
+
+    for pid, perm in seen.items():
+        if status:
+            async with async_session() as session:
+                proj = await session.get(Project, pid)
+            if not proj or proj.status != status:
+                continue
+        else:
+            async with async_session() as session:
+                proj = await session.get(Project, pid)
+        if proj:
+            d = proj.to_dict() if hasattr(proj, "to_dict") else {"id": proj.id, "title": proj.title}
+            d["permission"] = perm
+            d["is_shared"] = True
+            result.append(d)
+
+    return result