Add Layouts module with Konva.js builder; smart offline polling; UI improvements

- Move board cards from dashboard to top of boards list page
- Fix Werkzeug duplicate polling (WERKZEUG_RUN_MAIN guard)
- Smart offline polling: fast loop for online boards, slow recheck for offline
- Add manual ping endpoint POST /api/boards/<id>/ping
- Add spin animation CSS for ping button

Layouts module (new):
- app/models/layout.py: Layout model (canvas_json, thumbnail_b64)
- app/routes/layouts.py: 5 routes (list, create, builder, save, delete)
- app/templates/layouts/: list and builder templates
- app/static/js/layout_builder.js: full Konva.js builder engine
- app/static/vendor/konva/: vendored Konva.js 9
- Structure mode: wall, room, door, window, fence, text shapes
- Devices mode: drag relay/input/Sonoff channels onto canvas
- Live view mode: click relays/Sonoff to toggle, socket.io state updates
- Device selection: click to select, remove individual device, Delete key
- Fix door/Arc size persistence across save/reload (outerRadius, scaleX/Y)
- Fix Sonoff devices missing from palette (add makeSonoffChip function)

run.py

@@ -11,31 +11,48 @@ import threading
 import time
 
 from app import create_app, socketio
-from app.services.board_service import poll_all_boards
+from app.services.board_service import poll_online_boards, recheck_offline_boards
 
 app = create_app(os.environ.get("FLASK_ENV", "development"))
 
 
-def _background_poller():
-    """Poll all boards in a loop every BOARD_POLL_INTERVAL seconds."""
+def _online_poller():
+    """Fast loop — polls only online boards every BOARD_POLL_INTERVAL seconds."""
     interval = app.config.get("BOARD_POLL_INTERVAL", 10)
     while True:
         try:
-            poll_all_boards(app)
+            poll_online_boards(app)
         except Exception as exc:
-            app.logger.warning("Poller error: %s", exc)
+            app.logger.warning("Online poller error: %s", exc)
         time.sleep(interval)
 
 
+def _offline_recheck_poller():
+    """Slow loop — probes offline boards every OFFLINE_RECHECK_INTERVAL seconds.
+
+    Waits one full interval before the first check so startup is clean.
+    """
+    interval = app.config.get("OFFLINE_RECHECK_INTERVAL", 60)
+    while True:
+        time.sleep(interval)  # wait first, then check
+        try:
+            recheck_offline_boards(app)
+        except Exception as exc:
+            app.logger.warning("Offline recheck error: %s", exc)
+
+
 def create_socketio_app():
     """WSGI callable for gunicorn / production."""
     return socketio.middleware(app)
 
 
 if __name__ == "__main__":
-    # Start background board poller
-    t = threading.Thread(target=_background_poller, daemon=True)
-    t.start()
+    # Werkzeug debug-reloader starts two processes; only start the poller in
+    # the actual worker (WERKZEUG_RUN_MAIN=true) to avoid duplicate polling.
+    # In non-debug mode (WERKZEUG_RUN_MAIN is unset) we always start it.
+    if not app.debug or os.environ.get("WERKZEUG_RUN_MAIN") == "true":
+        threading.Thread(target=_online_poller, daemon=True).start()
+        threading.Thread(target=_offline_recheck_poller, daemon=True).start()
 
     port = int(os.environ.get("PORT", 5000))
     socketio.run(app, host="0.0.0.0", port=port, debug=app.debug, allow_unsafe_werkzeug=True)