feat: per-role inject_mode, OTR fixes, hover metadata, send/stop tooltip

- inject_mode: per-role toggle (parallel to inject_datetime) gates the
  "Current mode: Off The Record" line in the system prompt; wired through
  model_registry, context_loader, chat router, orchestrator router, and
  local_llm settings UI

- OTR orchestrator fix: OrchestrateRequest now carries off_record;
  _finalize_job stores it per message and gates log_turn on it; JS
  orchestrate payload sends off_record correctly

- Per-message hover metadata: removed always-visible .model-tag; replaced
  with .msg-meta strip in the action bar (hover-only); shows model label,
  host, fallback indicator, and OTR badge; stored in session JSON

- Send/stop button tooltip: shows role + model and (when tools on)
  separate orchestrator model + engine label; live elapsed timer on stop
  button via startRunTimer/stopRunTimer

- OrchestratorResult.backend_label: new field; openai_orchestrator fills
  it; finalize_job propagates it to job dict and session messages

- GET /backend: exposes orchestrator_model label so the frontend tooltip
  can show both models separately

- TODO: session delete confirmation added

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

cortex/routers/chat.py

@@ -14,6 +14,7 @@ from persona import set_context, validate as validate_persona
 from auth_utils import COOKIE_NAME, decode_token
 import model_registry
 import event_bus
+from model_registry import get_role_config
 
 
 router = APIRouter()
@@ -90,15 +91,18 @@ async def _stream_chat(req: ChatRequest):
     session_id = req.session_id or generate_session_id()
     tier = req.tier or settings.default_tier
 
+    role_cfg = get_role_config(user, req.chat_role)
     system_prompt = load_context(
         tier,
         include_long=req.include_long,
         include_mid=req.include_mid,
         include_short=req.include_short,
+        inject_datetime=role_cfg.get("inject_datetime", True),
+        inject_mode=role_cfg.get("inject_mode", True),
         mode="otr" if req.off_record else "chat",
     )
     history = load_session(session_id)
-    history.append({"role": "user", "content": req.message})
+    history.append({"role": "user", "content": req.message, "off_record": req.off_record})
 
     task = asyncio.create_task(complete(
         system_prompt=system_prompt,
@@ -128,6 +132,7 @@ async def _stream_chat(req: ChatRequest):
                 "backend": actual_backend,
                 "backend_label": backend_label,
                 "host": host,
+                "off_record": req.off_record,
             })
             save_session(session_id, history)
             if not req.off_record:
@@ -228,8 +233,16 @@ async def get_backend(request: Request) -> dict:
     username        = _request_user(request)
     available_roles = _available_roles_for_toggle(username) if username else []
     p = settings.primary_backend
+
+    orch_label = None
+    if username:
+        orch_cfg = model_registry.get_model_for_role(username, "orchestrator")
+        if orch_cfg:
+            orch_label = orch_cfg.get("label") or orch_cfg.get("model_name") or None
+
     return {
-        "available_roles": available_roles,
+        "available_roles":   available_roles,
+        "orchestrator_model": orch_label,
         # Legacy fields kept for backward compat
         "primary":     p,
         "fallback":    _BACKEND_FALLBACK.get(p, "claude"),