fix: local json import in graduation request/status handlers

NameError on /admin/graduation/request — routes.py doesn't import json
at module scope. Added local 'import json as _json' in both graduation
handlers matching the pattern used elsewhere in this file.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

src/atocore/api/routes.py

@@ -1372,11 +1372,12 @@ def api_request_graduation(req: GraduationRequestBody) -> dict:
     Mirrors the /admin/triage/request-drain pattern (bridges container
     → host because claude CLI lives on host, not container).
     """
+    import json as _json
     from datetime import datetime as _dt, timezone as _tz
     from atocore.context.project_state import set_state
 
     now = _dt.now(_tz.utc).strftime("%Y-%m-%dT%H:%M:%SZ")
-    payload = json.dumps({
+    payload = _json.dumps({
         "project": (req.project or "").strip(),
         "limit": max(1, min(req.limit, 500)),
         "requested_at": now,
@@ -1399,6 +1400,7 @@ def api_request_graduation(req: GraduationRequestBody) -> dict:
 @router.get("/admin/graduation/status")
 def api_graduation_status() -> dict:
     """State of the graduation pipeline (UI polling)."""
+    import json as _json
     from atocore.context.project_state import get_state
     out = {
         "requested": None,
@@ -1413,7 +1415,7 @@ def api_graduation_status() -> dict:
                 continue
             if e.key == "graduation_requested_at":
                 try:
-                    out["requested"] = json.loads(e.value)
+                    out["requested"] = _json.loads(e.value)
                 except Exception:
                     out["requested"] = {"raw": e.value}
             elif e.key == "graduation_last_started_at":