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/services/notes.py

@@ -63,7 +63,6 @@ async def create_note(
     due_date: date | None = None,
     recurrence_rule: dict | None = None,
     note_type: str = "note",
-    entity_meta: dict | None = None,
     task_kind: str = "work",
     arose_from_id: int | None = None,
 ) -> Note:
@@ -107,7 +106,6 @@ async def create_note(
             due_date=due_date,
             recurrence_rule=recurrence_rule,
             note_type=note_type,
-            entity_meta=entity_meta,
             task_kind=task_kind,
             arose_from_id=arose_from_id,
         )