fix(mcp): make get_note / get_task share-aware

The injected menu tells the agent to open any hit with get_note(id), and
that menu can list a collaborator's record reached through a shared
project. The fetch was still owner-only, so those lines answered
"not found" — for a record the same user opens fine in the browser.
The agent path was strictly narrower than the web path for the same id.

Same boundary miss as #2093: the list side was widened for sharing, the
fetch side wasn't. Both tools now resolve through get_note_for_user,
apply the trash filter themselves (permission resolution says nothing
about liveness), and attach describe_provenance so a shared record
arrives marked as someone else's rather than passing as the caller's.

routes/tasks.py's parent-title lookup had the same narrowness: a shared
subtask rendered as an orphan when its parent was equally shared.

Four fetch tests across three files were patching notes_svc.get_note and
had to be retargeted — note 2109's third sub-case, caught by grepping
tests/ for the old name before pushing rather than by CI (#2159).

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01RLwAaV4DQEmVyn496HnEvt

src/scribe/mcp/tools/notes.py

@@ -14,6 +14,7 @@ Sentinel conventions (inherited from existing fable-mcp tools):
 from __future__ import annotations
 
 from scribe.mcp._context import current_user_id
+from scribe.services import access as access_svc
 from scribe.services import dedup as dedup_svc
 from scribe.services import notes as notes_svc
 from scribe.services import systems as systems_svc
@@ -57,12 +58,17 @@ async def get_note(note_id: int) -> dict:
     """Fetch the full content of a single Scribe note by its ID.
 
     Returns id, title, body (markdown), tags, project_id, created_at, updated_at.
+    A note another user shared with you also carries `shared`, `owner` and
+    `permission` — read it as their suggestion, not as settled practice you set.
     """
     uid = current_user_id()
-    note = await notes_svc.get_note(uid, note_id)
-    if note is None:
+    loaded = await notes_svc.get_note_for_user(uid, note_id)
+    note = loaded[0] if loaded else None
+    if note is None or note.deleted_at is not None:
         raise ValueError(f"note {note_id} not found")
-    return note.to_dict()
+    out = note.to_dict()
+    out.update(await access_svc.describe_provenance(uid, note))
+    return out
 
 
 async def create_note(