feat: add FastAPI model/load endpoint and all Next.js proxy routes (tasks 2-4)

openspec/changes/ml-ui-connection/tasks.md

@@ -7,25 +7,25 @@
 
 ## 2. FastAPI Training Endpoints
 
-- [ ] 2.1 Add `POST /training/start` endpoint that launches training in a background thread, returns `{run_id, status: "running"}`, and rejects concurrent runs with HTTP 409
-- [ ] 2.2 Add `GET /training/runs` endpoint returning training run history from the `training_runs` table, sorted by date descending
-- [ ] 2.3 Add `GET /training/dataset-info` endpoint returning labeled dataset file path, existence, size, and row count
-- [ ] 2.4 Add background training thread management: track active run, update DB status on completion/failure
+- [x] 2.1 Add `POST /training/start` endpoint that launches training in a background thread, returns `{run_id, status: "running"}`, and rejects concurrent runs with HTTP 409
+- [x] 2.2 Add `GET /training/runs` endpoint returning training run history from the `training_runs` table, sorted by date descending
+- [x] 2.3 Add `GET /training/dataset-info` endpoint returning labeled dataset file path, existence, size, and row count
+- [x] 2.4 Add background training thread management: track active run, update DB status on completion/failure
 
 ## 3. FastAPI Model Loading Endpoint
 
-- [ ] 3.1 Add `POST /model/load` endpoint accepting `{run_id}`, looking up the training run, loading the model artifact, and replacing the active model in `AppState`
-- [ ] 3.2 Add thread-safe model swap with locking to prevent conflicts with in-flight prediction requests
+- [x] 3.1 Add `POST /model/load` endpoint accepting `{run_id}`, looking up the training run, loading the model artifact, and replacing the active model in `AppState`
+- [x] 3.2 Add thread-safe model swap with locking to prevent conflicts with in-flight prediction requests
 
 ## 4. Next.js Proxy Routes
 
-- [ ] 4.1 Add `GET /api/patterns/available` proxy route
-- [ ] 4.2 Add `POST /api/patterns/detect` proxy route
-- [ ] 4.3 Add `POST /api/training/start` proxy route
-- [ ] 4.4 Add `GET /api/training/runs` proxy route
-- [ ] 4.5 Add `GET /api/training/dataset-info` proxy route
-- [ ] 4.6 Add `POST /api/model/load` proxy route
-- [ ] 4.7 Extend `DELETE /api/span-annotations` to support `source` and `label` query parameters for bulk deletion
+- [x] 4.1 Add `GET /api/patterns/available` proxy route
+- [x] 4.2 Add `POST /api/patterns/detect` proxy route
+- [x] 4.3 Add `POST /api/training/start` proxy route
+- [x] 4.4 Add `GET /api/training/runs` proxy route
+- [x] 4.5 Add `GET /api/training/dataset-info` proxy route
+- [x] 4.6 Add `POST /api/model/load` proxy route
+- [x] 4.7 Extend `DELETE /api/span-annotations` to support `source` and `label` query parameters for bulk deletion
 
 ## 5. TA-Lib Pattern UI Panel