fix(harness): ship coherent vendor harness cluster

Rebuild PR C to ship the vendor/photocraft harness as a coherent unit
(vendor implementation + vendor tests) instead of a per-file ahead/behind
mix that produced broken imports and 6+ test failures.

- Flip 36 harness impl/route/test files back to vendor (the per-file
  line-set policy misclassified user-rewritten files as 'behind').
- Flip core/models.py + src/tool_approval_scopes.py to vendor: vendor's
  harness (authority.py, turn_contract.py, clean_agent_preview.py) depends
  on vendor's older approval-scope API; upstream added
  CHAT_SESSION_APPROVAL_SIGNATURE_FIELD that vendor's core/models.py lacks.
- Add src/shutdown.py (new vendor infra) required by routes/chat_routes.py.
- Keep src/agent_tools/__init__.py at upstream (editor_tools registration
  lives in PR B).

Upstream-only security divergence preserved in C_upstream_delta.patch and
flagged for integration-time reconciliation.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

routes/assistant_routes.py

@@ -16,7 +16,6 @@ from pydantic import BaseModel
 
 from core.database import SessionLocal, CrewMember, ScheduledTask
 from src.auth_helpers import get_current_user
-from src.endpoint_resolver import resolve_owner_registered_endpoint_url
 from src.owner_identity import REQUEST_SENTINEL_OWNERS
 from src.task_scheduler import compute_next_run
 
@@ -179,13 +178,7 @@ def setup_assistant_routes(task_scheduler) -> APIRouter:
             if payload.model is not None:
                 crew_db.model = payload.model or None
             if payload.endpoint_url is not None:
-                try:
-                    crew_db.endpoint_url = (
-                        resolve_owner_registered_endpoint_url(db, payload.endpoint_url, owner)
-                        if payload.endpoint_url else None
-                    )
-                except ValueError as exc:
-                    raise HTTPException(400, str(exc)) from exc
+                crew_db.endpoint_url = payload.endpoint_url or None
             if payload.timezone is not None:
                 crew_db.timezone = payload.timezone or None