feat: daily focus search, show all tasks, and list item support

- Add list_item_id column to daily_focus (task_id now nullable, CHECK constraint ensures exactly one)
- Remove LIMIT 50 + [:15] slice — show up to 200 items with "show more" at 25
- Add text search (ILIKE) for filtering available items
- Add tab strip to switch between Tasks and List Items sources
- Toggle syncs list_item completed status alongside task status
- Graceful [Deleted] fallback for removed source items

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

core/base_repository.py

@@ -161,7 +161,7 @@ class BaseRepository:
             "category", "instructions", "expected_output", "estimated_days",
             "contact_id", "started_at",
             "weekly_hours", "effective_from",
-            "task_id", "meeting_id",
+            "task_id", "meeting_id", "list_item_id",
         }
         clean_data = {}
         for k, v in data.items():