fix(contract-drift): MCP read-only scope, shared-note writes, event TZ

Drift-audit Group 5 (high-severity contract drift):

- MCP read-only keys could call every write tool: the Bearer resolver
  discarded api_key.scope and dispatch had no gate. Add resolve_bearer()
  (returns user_id + scope) and a scope gate in the /mcp ASGI wrapper that
  buffers the JSON-RPC body and rejects tools/call for any tool outside a
  read all-list when scope=='read' (default-deny for unknown/new tools).
- Shared project notes/tasks panel was empty for non-owners: get_project_notes_route
  now queries notes/milestones with the project OWNER's uid (mirrors the
  already-fixed milestones route).
- Shared editors couldn't save/delete shared NOTES (tasks worked): the three
  notes write routes now resolve via get_note_for_user, gate on can_write_note,
  and write as the owner — matching the tasks routes.
- Event timezone drift: naive datetimes from the MCP date+time split are now
  localized to the user's tz at a single canonical service point (create_event
  /update_event), so MCP- and UI-created events agree. tz-aware inputs
  (REST/CalDAV) pass through untouched.
- create_note validates status/priority (TaskStatus/TaskPriority), closing the
  MCP create_task path that let out-of-enum values persist (no DB CHECK).

Tests cover resolve_bearer scope + the write-tool classifier.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

src/fabledassistant/routes/projects.py

@@ -116,6 +116,9 @@ async def get_project_notes_route(project_id: int):
     if result is None:
         return not_found("Project")
     project, _ = result
+    # Use the project owner's uid so the ownership filter on notes/milestones
+    # matches for shared collaborators (who'd otherwise see an empty panel).
+    owner_uid = project.user_id or uid
 
     # type filter: "note", "task", or None (both)
     type_filter = request.args.get("type")
@@ -128,11 +131,11 @@ async def get_project_notes_route(project_id: int):
     elif type_filter == "note":
         is_task = False
 
-    ms_list = await list_milestones(uid, project_id)
+    ms_list = await list_milestones(owner_uid, project_id)
     milestone_ids = [m.id for m in ms_list]
 
     notes, total = await list_notes(
-        uid,
+        owner_uid,
         is_task=is_task,
         status=status_filter,
         project_id=project_id,