docs(scanner): Beam batch 7 — all 10 scanner endpoints backfilled

Scanner surface frontmatter'd (scan/start/stop/cancel/status/active/
active-summary + watch start/stop/status) with provenance comments;
active-summary on a non-admin group.

Claude registry: 10 entries. Fixed handler drift Beam missed: scan_library
request has no "recursive"; scanner/start binds folder_paths (not
invented interval_seconds); scanner/stop binds no body; response is
{message, job_id, status} with 409 coalescing variant
{error, active_job_id}.

Gate fix in drift_test seed: registerScannerRoutes group seeds used bare
"jwt"/"admin" tokens invisible to authLabel; and silently passed before
only because the seeded set was unchecked. Seeds now 'jwtMiddleware'/
'AdminMiddleware' markers. Also: cleanup of a stale-merge-script residue
in collections/update_rule.md example (extra null keys). make test 9/9.

docs/developer/api/scanner/get_scan_status.md

@@ -1,3 +1,11 @@
+---
+method: GET
+path: /api/scanner/status/:jobId
+auth: jwt+admin
+area: scanner
+---
+<!-- source: internal/handlers/scanner.go:179 Handler.GetScanStatus -->
+
 # Get Scan Status
 
 Get the status of a specific scan job.
@@ -26,13 +34,10 @@ Authorization: Bearer eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9...
 
 ## Response (200 OK)
 
-```json
+```json example-response
 {
   "job_id": "uuid",
-  "library_id": "uuid",
   "status": "in_progress",
-  "started_at": "2026-02-08T10:00:00Z",
-  "updated_at": "2026-02-08T10:05:00Z",
   "progress": {
     "total_files": 1523,
     "scanned_files": 850,
@@ -46,7 +51,11 @@ Authorization: Bearer eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9...
       "file_path": "/path/to/file.epub",
       "error": "Invalid EPUB format"
     }
-  ]
+  ],
+  "error": null,
+  "files_scanned": null,
+  "new_items": null,
+  "result": null
 }
 ```