feat: add more easter eggs

lib/views/bar/product_grid.dart

@@ -1,3 +1,4 @@
+import 'dart:async';
 import 'dart:math';
 
 import 'package:flutter/material.dart';
@@ -147,10 +148,15 @@ class ProductGrid extends StatelessWidget {
                 itemBuilder: (context, index) {
                   final product = products[index];
 
-                  return ProductTile(
-                    product: product,
+                  return _FireTile(
+                    key: ValueKey(product.id),
                     enabled: hasSelectedTab,
                     onTap: () => onProductTap(product),
+                    builder: (onTap) => ProductTile(
+                      product: product,
+                      enabled: hasSelectedTab,
+                      onTap: onTap,
+                    ),
                   );
                 },
               );
@@ -161,3 +167,128 @@ class ProductGrid extends StatelessWidget {
     );
   }
 }
+
+/// Five quick taps on the same product set its tile on fire for a moment.
+class _FireTile extends StatefulWidget {
+  final bool enabled;
+  final VoidCallback onTap;
+  final Widget Function(VoidCallback onTap) builder;
+
+  const _FireTile({
+    super.key,
+    required this.enabled,
+    required this.onTap,
+    required this.builder,
+  });
+
+  @override
+  State<_FireTile> createState() => _FireTileState();
+}
+
+class _FireTileState extends State<_FireTile>
+    with SingleTickerProviderStateMixin {
+  static const _tapsNeeded = 5;
+  static const _tapWindow = Duration(milliseconds: 700);
+  static const _burnTime = Duration(milliseconds: 2500);
+
+  late final AnimationController _flicker = AnimationController(
+    vsync: this,
+    duration: const Duration(milliseconds: 180),
+  );
+
+  int _tapCount = 0;
+  DateTime? _lastTap;
+  Timer? _burnTimer;
+
+  bool get _isOnFire => _burnTimer != null;
+
+  @override
+  void dispose() {
+    _burnTimer?.cancel();
+    _flicker.dispose();
+    super.dispose();
+  }
+
+  void _onTap() {
+    widget.onTap();
+
+    final now = DateTime.now();
+    final last = _lastTap;
+    _tapCount = last != null && now.difference(last) < _tapWindow
+        ? _tapCount + 1
+        : 1;
+    _lastTap = now;
+    if (_tapCount < _tapsNeeded && !_isOnFire) return;
+
+    // Each extra quick tap keeps it burning.
+    _burnTimer?.cancel();
+    _burnTimer = Timer(_burnTime, () {
+      if (!mounted) return;
+      _flicker.stop();
+      setState(() => _burnTimer = null);
+    });
+    if (!_flicker.isAnimating) _flicker.repeat(reverse: true);
+    setState(() {});
+  }
+
+  @override
+  Widget build(BuildContext context) {
+    return Stack(
+      fit: StackFit.expand,
+      clipBehavior: Clip.none,
+      children: [
+        widget.builder(_onTap),
+        IgnorePointer(
+          child: AnimatedOpacity(
+            opacity: _isOnFire ? 1 : 0,
+            duration: const Duration(milliseconds: 300),
+            child: AnimatedBuilder(
+              animation: _flicker,
+              builder: (context, _) {
+                final heat = _flicker.value;
+
+                return Stack(
+                  fit: StackFit.expand,
+                  clipBehavior: Clip.none,
+                  children: [
+                    DecoratedBox(
+                      decoration: BoxDecoration(
+                        borderRadius: BorderRadius.circular(16),
+                        border: Border.all(
+                          color: Color.lerp(
+                            Colors.deepOrange,
+                            Colors.amber,
+                            heat,
+                          )!,
+                          width: 2.5,
+                        ),
+                        boxShadow: [
+                          BoxShadow(
+                            color: Colors.deepOrange.withValues(
+                              alpha: 0.45 + 0.3 * heat,
+                            ),
+                            blurRadius: 14 + 10 * heat,
+                            spreadRadius: 1 + 2 * heat,
+                          ),
+                        ],
+                      ),
+                    ),
+                    Positioned(
+                      left: 8,
+                      bottom: 6,
+                      child: Transform.scale(
+                        scale: 1 + 0.15 * heat,
+                        alignment: Alignment.bottomCenter,
+                        child: const Text('🔥', style: TextStyle(fontSize: 26)),
+                      ),
+                    ),
+                  ],
+                );
+              },
+            ),
+          ),
+        ),
+      ],
+    );
+  }
+}