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>

runtime/plan_agent_v2/compat.py

@@ -0,0 +1,45 @@
+from __future__ import annotations
+
+from typing import Any
+
+from .adapter import PlanAgentV2Decision
+from oclaw.runtime.gateway import OclawGatewayResult
+
+
+def legacy_gateway_result_keys() -> set[str]:
+    return set(OclawGatewayResult.__dataclass_fields__.keys())
+
+
+def build_shadow_gateway_result(
+    *,
+    decision: PlanAgentV2Decision,
+    run_id: str,
+    trace_id: str,
+    elapsed_ms: int,
+    requested_specialist: str,
+) -> dict[str, Any]:
+    return {
+        "run_id": str(run_id),
+        "reply_text": str(decision.reply_text or ""),
+        "trace_id": str(trace_id),
+        "elapsed_ms": int(elapsed_ms),
+        "mode": "sync_direct",
+        "task_id": None,
+        "selected_specialist": str((decision.plan_state or {}).get("owner_specialist") or requested_specialist or "generalist"),
+        "interaction_mode": "expert",
+        "dispatch_reason": f"plan_agent_v2:{decision.action}",
+        "manager_selected_specialist": str((decision.plan_state or {}).get("owner_specialist") or requested_specialist or "generalist"),
+        "requested_specialist": str(requested_specialist or "generalist"),
+        "dynamic_agent_used": False,
+        "dynamic_agent_name": "",
+        "relay_pointer_count": 0,
+        "relay_envelope_present": False,
+        "relay_envelope_pointer_count": 0,
+        "relay_ttl_turn_count": 0,
+        "relay_ttl_session_count": 0,
+        "relay_ttl_keep_count": 0,
+    }
+
+
+__all__ = ["build_shadow_gateway_result", "legacy_gateway_result_keys"]
+