feat: juice kit - sparks, score popups, combo banners, confetti, haptics, shake

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

lib/ui/screens/game_screen.dart

@@ -1,4 +1,7 @@
+import 'dart:math' as math;
+
 import 'package:flutter/material.dart';
+import 'package:flutter/services.dart';
 import 'package:flutter_riverpod/flutter_riverpod.dart';
 
 import '../../game/engine/game_engine.dart';
@@ -10,6 +13,7 @@ import '../theme/palette.dart';
 import '../widgets/board_geometry.dart';
 import '../widgets/board_painter.dart';
 import '../widgets/board_widget.dart';
+import '../widgets/effects_overlay.dart';
 import '../widgets/hud_widget.dart';
 import '../widgets/piece_painter.dart';
 import '../widgets/season_background.dart';
@@ -24,9 +28,15 @@ class GameScreen extends ConsumerStatefulWidget {
   ConsumerState<GameScreen> createState() => _GameScreenState();
 }
 
-class _GameScreenState extends ConsumerState<GameScreen> {
+class _GameScreenState extends ConsumerState<GameScreen>
+    with TickerProviderStateMixin {
   final _boardKey = GlobalKey();
   final _stackKey = GlobalKey();
+  final _effectsKey = GlobalKey<EffectsOverlayState>();
+  late final AnimationController _shake = AnimationController(
+    vsync: this,
+    duration: const Duration(milliseconds: 350),
+  );
 
   int? _dragIndex;
   Offset? _dragGlobal;
@@ -94,6 +104,12 @@ class _GameScreenState extends ConsumerState<GameScreen> {
     }
   }
 
+  @override
+  void dispose() {
+    _shake.dispose();
+    super.dispose();
+  }
+
   void _onSessionChange(GameViewState? prev, GameViewState? next) {
     if (next == null) return;
     final audio = ref.read(audioServiceProvider);
@@ -101,8 +117,25 @@ class _GameScreenState extends ConsumerState<GameScreen> {
       final placement = next.lastPlacement!;
       if (placement.linesCleared > 0) {
         audio.play(placement.comboStreak >= 2 ? Sfx.combo : Sfx.clear);
+        HapticFeedback.mediumImpact();
+        if (placement.comboStreak >= 4) {
+          HapticFeedback.heavyImpact();
+          _shake.forward(from: 0);
+        }
       } else {
         audio.play(Sfx.place);
+        HapticFeedback.lightImpact();
+      }
+      final boardBox = _boardBox;
+      final stackBox =
+          _stackKey.currentContext?.findRenderObject() as RenderBox?;
+      if (boardBox != null && stackBox != null) {
+        final topLeft =
+            stackBox.globalToLocal(boardBox.localToGlobal(Offset.zero));
+        _effectsKey.currentState?.onPlacement(
+          placement,
+          boardRect: topLeft & boardBox.size,
+        );
       }
     }
     if (prev?.phase != next.phase) {
@@ -112,6 +145,11 @@ class _GameScreenState extends ConsumerState<GameScreen> {
         ref
             .read(seasonFlowProvider.notifier)
             .recordWin(stars: next.starsEarned, score: next.score);
+        final stackBox =
+            _stackKey.currentContext?.findRenderObject() as RenderBox?;
+        if (stackBox != null) {
+          _effectsKey.currentState?.onWin(stackBox.size);
+        }
       }
       if (next.phase == GamePhase.lost) audio.play(Sfx.lose);
       if (next.phase == GamePhase.won || next.phase == GamePhase.lost) {
@@ -159,10 +197,20 @@ class _GameScreenState extends ConsumerState<GameScreen> {
                       HudWidget(view: view),
                       Expanded(
                         child: Center(
-                          child: BoardWidget(
-                            key: _boardKey,
-                            view: view,
-                            ghost: ghost,
+                          child: AnimatedBuilder(
+                            animation: _shake,
+                            builder: (context, child) {
+                              final t = _shake.value;
+                              final dx =
+                                  math.sin(t * math.pi * 10) * 6 * (1 - t);
+                              return Transform.translate(
+                                  offset: Offset(dx, 0), child: child);
+                            },
+                            child: BoardWidget(
+                              key: _boardKey,
+                              view: view,
+                              ghost: ghost,
+                            ),
                           ),
                         ),
                       ),
@@ -185,6 +233,7 @@ class _GameScreenState extends ConsumerState<GameScreen> {
                     boardBox != null &&
                     _dragIndex! < view.tray.length)
                   _draggedPieceOverlay(view, draggedTopLeft, boardBox),
+                Positioned.fill(child: EffectsOverlay(key: _effectsKey)),
                 if (view.phase != GamePhase.playing) _resultOverlay(view),
                 if (Navigator.of(context).canPop())
                   Positioned(