Implement historical tracking using django-pghistory; add middleware for context capture and update model architecture

memory-bank/systemPatterns.md

@@ -36,7 +36,23 @@
    - Use Redis for session storage
    - Cache invalidation rules
 
-### Frontend Patterns
+### Historical Tracking
+- All model changes create immutable pghistory events
+- Events contain:
+  - Full object state snapshot
+  - Contextual metadata (user, request fingerprint)
+  - Semantic event label (created, updated, deleted)
+- Middleware integration:
+  ```python
+  # core/middleware.py
+  pghistory.context(lambda request: {
+      'user': str(request.user) if request.user.is_authenticated else None,
+      'ip': request.META.get('REMOTE_ADDR'),
+      'user_agent': request.META.get('HTTP_USER_AGENT')
+  })
+  ```
+
+## Frontend Patterns
 
 1. HTMX Integration
    ```html