feat: task queue system with startup drain and backlogging (#76)

* feat: add task queue system for Timmy - all work goes through the queue

- Add queue position tracking to task_queue models with task_type field
- Add TaskProcessor class that consumes tasks from queue one at a time
- Modify chat route to queue all messages for async processing
- Chat responses get 'high' priority to jump ahead of thought tasks
- Add queue status API endpoints for position polling
- Update UI to show queue position (x/y) and current task banner
- Replace thinking loop with task-based approach - thoughts are queued tasks
- Push responses to user via WebSocket instead of immediate HTTP response
- Add database migrations for existing tables

* feat: Timmy drains task queue on startup, backlogs unhandleable tasks

On spin-up, Timmy now iterates through all pending/approved tasks
immediately instead of waiting for the polling loop. Tasks without a
registered handler or with permanent errors are moved to a new
BACKLOGGED status with a reason, keeping the queue clear for work
Timmy can actually do.

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

---------

Co-authored-by: Alexander Payne <apayne@MM.local>
Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>

memory/self/user_profile.md

@@ -4,7 +4,7 @@
 
 ## Basic Information
 
-**Name:** TestUser
+**Name:** Not
 **Location:** (unknown)  
 **Occupation:** (unknown)  
 **Technical Level:** (to be assessed)
@@ -40,4 +40,4 @@
 
 ---
 
-*Last updated: 2026-02-25*
+*Last updated: 2026-02-27*