fix: rename Note.metadata → entity_meta (reserved by SQLAlchemy Declarative API)

SQLAlchemy reserves 'metadata' as a class attribute on declarative models.
Renamed to 'entity_meta' with explicit column name 'metadata' so the DB
column is unchanged but the Python attribute no longer conflicts.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/fabledassistant/services/notes.py

@@ -58,7 +58,7 @@ async def create_note(
     due_date: date | None = None,
     recurrence_rule: dict | None = None,
     note_type: str = "note",
-    metadata: dict | None = None,
+    entity_meta: dict | None = None,
 ) -> Note:
     # Auto-populate project_id from milestone when not explicitly provided
     if milestone_id is not None and project_id is None:
@@ -85,7 +85,7 @@ async def create_note(
             due_date=due_date,
             recurrence_rule=recurrence_rule,
             note_type=note_type,
-            metadata=metadata,
+            entity_meta=entity_meta,
         )
         session.add(note)
         await session.commit()