feat(watcher): add configurable IdleTimeoutMs setting (default 5 min)

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

WindowWatcher/WindowWatcherOptions.cs

@@ -7,4 +7,5 @@ public class WindowWatcherOptions
     public string ApiBaseUrl { get; set; } = "http://localhost:5200";
     public int PollIntervalMs { get; set; } = 2000;
     public int DebounceMs { get; set; } = 3000;
+    public int IdleTimeoutMs { get; set; } = 300_000;
 }

WindowWatcher/appsettings.json

@@ -8,6 +8,7 @@
   "WindowWatcher": {
     "ApiBaseUrl": "http://localhost:5200",
     "PollIntervalMs": 2000,
-    "DebounceMs": 3000
+    "DebounceMs": 3000,
+    "IdleTimeoutMs": 300000
   }
 }