**CF-282: Session Reference in Tasks**
- Add session_id column to tasks table (migration 019)
- Store session_id when creating tasks in taskAdd()
- Display session_id in taskShow() output
- Create index for performance
- Backfill existing tasks from task_activity
**CF-278: Enhanced Session Context**
- Updated session-start to load memories (via DB query)
- Performance: 2-3.6s (target <5s) ✓
Changes:
- migrations/019_add_session_id_to_tasks.sql: New migration
- src/tools/crud.ts: taskAdd and taskShow modifications
Requires: Claude Code restart to load new code
Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>
