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/history/history_routes.py

@@ -7,14 +7,13 @@ import logging
 import re
 from typing import Dict, Any, Optional
 
-from fastapi import APIRouter, Request, HTTPException, Depends
+from fastapi import APIRouter, Request, HTTPException
 
 from core.models import ChatMessage
 from core.database import SessionLocal, ChatMessage as DbChatMessage, Session as DbSession
-from src.auth_helpers import effective_user, require_chat_api_token_scope
+from src.auth_helpers import effective_user
 from src.topic_analyzer import analyze_topics
 from src.upload_handler import reserve_message_upload_references
-from src.tool_approval_scopes import sanitize_client_message_metadata
 from routes.session_routes import (
     _message_role,
     _message_text,
@@ -238,10 +237,7 @@ def _keep_count_before_message(db_messages, before_msg_id: str | None) -> int |
 
 
 def setup_history_routes(session_manager, upload_handler=None) -> APIRouter:
-    router = APIRouter(
-        tags=["history"],
-        dependencies=[Depends(require_chat_api_token_scope)],
-    )
+    router = APIRouter(tags=["history"])
 
     def _reserve_message_uploads(
         request: Request,
@@ -436,7 +432,7 @@ def setup_history_routes(session_manager, upload_handler=None) -> APIRouter:
             content = body.get("content", "")
             if not content:
                 raise HTTPException(400, "content is required")
-            metadata = sanitize_client_message_metadata(body.get("metadata"))
+            metadata = body.get("metadata")
             _reserve_message_uploads(request, content, metadata)
             msg = ChatMessage(role=role, content=content, metadata=metadata)
             session_manager.add_message(session_id, msg)