chore: update TODO.md with current implementation status (closes #54)

Checks off completed items:
- Container logs page
- Deployment cancellation (internal + user-facing endpoint)
- Deployment rollback to previous image
- Deploy cancellation context and partial build cleanup

Removes items per sneak's direction:
- Real-time deployment log streaming (polling sufficient, #70)

TODO.md

@@ -53,8 +53,8 @@
 - [x] Deployment logs storage
 - [x] View deployment history per app
 - [x] Container logs viewing
-- [ ] Deployment rollback to previous image
+- [x] Deployment rollback to previous image
-- [ ] Deployment cancellation
+- [x] Deployment cancellation
 
 ### Manual Container Controls
 - [x] Restart container
@@ -119,7 +119,6 @@
 - [x] Container logs page
 - [ ] Webhook event history page
 - [ ] Settings page (webhook secret, SSH public key)
-- [ ] Real-time deployment log streaming (WebSocket/SSE)
 
 ### Future Considerations
 - [ ] Multi-user support with roles
@@ -201,17 +200,17 @@ Protected Routes (require auth):
   - Validate paths before saving
 
 ### 3.2 Deployment Rollback
-- [ ] Add `previous_image_id` column to apps table
+- [x] Add `previous_image_id` column to apps table
   - Store last successful image ID before new deploy
-- [ ] Add `POST /apps/:id/rollback` endpoint
+- [x] Add `POST /apps/:id/rollback` endpoint
   - Stop current container
   - Start container with previous image
   - Create deployment record for rollback
-- [ ] Update deploy service to save previous image before building new one
+- [x] Update deploy service to save previous image before building new one
 
 ### 3.3 Deployment Cancellation
 - [x] Add cancellation context to deploy service
-- [ ] Add `POST /apps/:id/deployments/:id/cancel` endpoint
+- [x] Add `POST /apps/:id/deployments/:id/cancel` endpoint
 - [x] Handle cleanup of partial builds/containers
 
 ## Phase 4: Lower Priority (Nice to Have)
@@ -240,8 +239,6 @@ Protected Routes (require auth):
 - [ ] Add settings page
   - View/regenerate webhook secret
   - View SSH public key
-- [ ] Add real-time deployment log streaming
-  - WebSocket or SSE for live build output
 
 ### 4.4 Observability
 - [ ] Add structured logging for all operations