Refactor backend status handling and improve idle management

- Updated the idle-killer logic to treat SwarmUI `empty` and `disabled` states as busy, preventing unnecessary idle time during provisioning.
- Enhanced the `wait_backend_idle` function to recognize suspended backends as ready, improving resource utilization and user feedback.
- Refined the `install_swarm_comfy` script to skip installation when backends are already present, streamlining the setup process.
- Improved the `resolve_llm_runtime` function to prioritize live configuration over stale state notes, ensuring accurate runtime detection.
- Added tests to validate the new backend status handling and idle management logic, ensuring robustness and reliability.

src/gpu_rent/remote/install_swarm_comfy.py

@@ -452,11 +452,11 @@ def main() -> int:
     print(f"backend_status={bstat} venv={'yes' if comfy_venv_ok() else 'no'} "
           f"IsInstalled={settings_is_installed()}")
 
+    # Backends already registered (any non-empty status) + venv → skip InstallConfirmWS.
     if bstat == "idle":
-        print("Comfy backend already Idle — skip install")
+        print("backends present (idle/suspended) + skip install")
         return 0
     if bstat not in ("empty", "unknown") and not bstat.startswith("error:"):
-        # loading / running / etc. — installer not needed
         if comfy_venv_ok():
             print(f"backends present ({bstat}) + venv — skip install")
             return 0
@@ -471,19 +471,28 @@ def main() -> int:
         return 1
 
     if installed is True and comfy_venv_ok():
-        print("IsInstalled + venv — skip InstallConfirmWS (ждём Idle отдельно)")
+        print("IsInstalled + venv — skip InstallConfirmWS (ждём ready отдельно)")
         return 0
 
     if comfy_venv_ok() and bstat == "empty":
-        # Partial: script ran but backend never registered — still need install
-        # only if IsInstalled is false; otherwise user must add backend in UI.
         if installed is not True:
             print("venv есть, IsInstalled=false — запускаю InstallConfirmWS")
         else:
             return 1
 
-    sid = get_session(time.time() + 120)
-    run_install(sid)
+    marker = DATA / ".gpu-rent-comfy-installing"
+    try:
+        marker.write_text(f"{int(time.time())}\n", encoding="utf-8")
+    except OSError:
+        pass
+    try:
+        sid = get_session(time.time() + 120)
+        run_install(sid)
+    finally:
+        try:
+            marker.unlink(missing_ok=True)
+        except OSError:
+            pass
 
     # Confirm outcome
     time.sleep(3)