refactor(scribe): retire calendar/events + person/place/list entities (backend)

Narrow Scribe to a Claude-Code work system-of-record (milestone #194,
decision note #1759). Wholesale removal per rule #22 — backend + schema half.

Calendar/events + CalDAV: delete models/event, services/{events,caldav,
caldav_sync}, routes/events, mcp/tools/events; strip event branches from
backup (bump v3->v4), dashboard (upcoming_events), trash, recent, and the
mcp server read-only allowlist + instructions.

Typed entities (person/place/list): delete mcp/tools/entities; drop the
notes.metadata (entity_meta) column from model/service/routes and the
knowledge browse service. note_type STAYS — it also marks 'process' notes.

Scheduler: event_scheduler -> recurrence_scheduler, keeping only the
recurring-task spawn job (drops event reminders + CalDAV sync).

Schema: migration 0069 drops the events table + notes.metadata column +
orphan caldav settings rows (faithful downgrade recreates them).

KEEP: recurrence.py (task recurrence), notifications task reminders, graph
view, and every work surface. Frontend + plugin/docs true-up follow next.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01BPtbSzA4JLMAKgFZ8VTg7Q

src/scribe/routes/notes.py

@@ -95,7 +95,6 @@ async def create_note_route():
             project_id = proj.id
 
     note_type = data.get("note_type", "note")
-    entity_meta = data.get("metadata") or None
 
     try:
         note = await create_note(
@@ -111,7 +110,6 @@ async def create_note_route():
             priority=priority,
             due_date=due_date,
             note_type=note_type,
-            entity_meta=entity_meta,
         )
     except ValueError as e:
         return jsonify({"error": str(e)}), 400
@@ -206,9 +204,6 @@ async def update_note_route(note_id: int):
     for key in ("title", "body", "description", "parent_id", "project_id", "milestone_id", "status", "priority", "note_type"):
         if key in data:
             fields[key] = data[key]
-    if "metadata" in data:
-        fields["entity_meta"] = data["metadata"] or None
-
     if "due_date" in data:
         if data["due_date"]:
             result = parse_iso_date(data["due_date"], "due_date")
@@ -248,8 +243,6 @@ async def patch_note_route(note_id: int):
     for key in ("title", "body", "description", "parent_id", "project_id", "milestone_id", "status", "priority", "note_type"):
         if key in data:
             fields[key] = data[key]
-    if "metadata" in data:
-        fields["entity_meta"] = data["metadata"] or None
     if "due_date" in data:
         if data["due_date"]:
             result = parse_iso_date(data["due_date"], "due_date")