feat: plan agent v2, global chat mode, and user-mode v2 flag sync

- Add runtime/plan_agent_v2 package and shims; gateway/direct_loop/WS wiring

- Admin chat: interaction mode and specialist only in user menu; session API stores memory_mode and execution_mode only

- POST /admin/api/chat/user-mode mirrors plan_agent_version to AIA_EXPERT_PLAN_AGENT_V2_ENABLED (v2 to 1, v1 to 0)

- Composer cleanup (hidden mode select, no reasoning toggle in meta bar); tests and _local/system.env.example

Co-authored-by: Cursor <cursoragent@cursor.com>

interfaces/http/fastapi_app.py

@@ -1,5 +1,9 @@
 from __future__ import annotations
 
+from oclaw.platform.config.bootstrap_env import load_system_env
+
+load_system_env()
+
 import asyncio
 import os
 import shutil
@@ -280,6 +284,7 @@ def create_app() -> FastAPI:
 
 
 def main() -> int:
+    load_system_env()
     host = (os.getenv("AIA_ASSISTANT_GATEWAY_HOST") or "0.0.0.0").strip()
     port = int(os.getenv("AIA_ASSISTANT_GATEWAY_PORT") or "8787")
     try: