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)

app/routes/api.py

@@ -1,10 +1,12 @@
 """REST API – board webhook receiver and JSON relay control."""
 from datetime import datetime
-from flask import Blueprint, request, jsonify, abort
+from flask import Blueprint, request, jsonify, abort, current_app
+from flask_login import login_required
 
 from app import db, socketio
 from app.models.board import Board
 from app.services import workflow_engine
+from app.services.board_service import poll_board
 
 api_bp = Blueprint("api", __name__)
 
@@ -46,6 +48,28 @@ def webhook(board_id: int):
     return jsonify({"status": "ok"})
 
 
+# ── Manual ping / status check ───────────────────────────────────────────────
+
+@api_bp.route("/boards/<int:board_id>/ping", methods=["POST"])
+@login_required
+def ping_board(board_id: int):
+    """Trigger an immediate poll for any board (online or offline).
+
+    Called by the 'Check Status' button in the UI.  The poll result is both
+    returned as JSON *and* broadcast via socket.io so all open tabs update.
+    """
+    db.get_or_404(Board, board_id)  # 404 if unknown
+    poll_board(current_app._get_current_object(), board_id)
+    board = db.session.get(Board, board_id)
+    return jsonify({
+        "board_id": board.id,
+        "is_online": board.is_online,
+        "relay_states": board.relay_states,
+        "input_states": board.input_states,
+        "last_seen": board.last_seen.isoformat() if board.last_seen else None,
+    })
+
+
 # ── JSON relay status ─────────────────────────────────────────────────────────
 
 @api_bp.route("/boards/<int:board_id>/relays")