feat: 完成训练分级庆祝 (normal/first/milestone/record)

- normal: 12 条彩带
- record (破个人纪录): 24 条 + 横幅"🏆 新纪录!X秒"
- milestone (连击 7/14/30/50/100/365 天): 32 条 + 横幅
- first (首次训练): 40 条 + 横幅"🎉 第一次训练"

横幅 3.5s 后自动淡出,彩带时长随等级递增(2.4s → 4s)。

pages/timer/timer.js

@@ -20,6 +20,9 @@ Page({
     todayTarget: 0,
     planDay: 1,
     isFreeMode: false,
+    celebrationLevel: 'normal',  // normal / first / milestone / record
+    celebrationMessage: '',
+    confettiPieces: [],
     icons: iconsMod.build()
   },
 
@@ -92,7 +95,16 @@ Page({
         this._remind(tick)
       },
       onComplete: () => {
-        this.setData({ status: 'completed', isCompleted: true })
+        const elapsed = this._timer.elapsed
+        const { level, message } = this._detectCelebrationLevel(elapsed)
+        const confettiPieces = this._buildConfettiPieces(level)
+        this.setData({
+          status: 'completed',
+          isCompleted: true,
+          celebrationLevel: level,
+          celebrationMessage: message,
+          confettiPieces
+        })
         const s = storage.getSettings()
         if (s.vibrate) {
           try { wx.vibrateLong() } catch (e) {}
@@ -162,6 +174,53 @@ Page({
     }
   },
 
+  /**
+   * Detect which celebration level to show. Called at onComplete (BEFORE
+   * saveRecord fires in finishTraining), so stats reflect pre-save state.
+   *  - first:     user's very first training ever
+   *  - milestone: streak will hit a memorable number after this save
+   *  - record:    this duration beats the user's previous max
+   *  - normal:    everything else
+   */
+  _detectCelebrationLevel(elapsed) {
+    const stats = storage.getTotalStats()
+    const streak = storage.getStreak()
+    const nextStreak = (streak.lastDate && streak.count >= 1) ? streak.count + 1 : 1
+
+    if (stats.totalSessions === 0) {
+      return { level: 'first', message: '🎉 第一次训练!坚持就是胜利' }
+    }
+    if ([7, 14, 30, 50, 100, 365].includes(nextStreak)) {
+      return { level: 'milestone', message: `🔥 连续打卡 ${nextStreak} 天!` }
+    }
+    if (elapsed > stats.maxDuration) {
+      return { level: 'record', message: `🏆 新纪录!${elapsed}秒` }
+    }
+    return { level: 'normal', message: '完成!' }
+  },
+
+  /**
+   * Build the confetti piece list. More pieces + more colors for higher
+   * celebration levels. Pieces are pre-positioned so the layout doesn't
+   * shift when wx:for renders them.
+   */
+  _buildConfettiPieces(level) {
+    const counts = { normal: 12, record: 24, milestone: 32, first: 40 }
+    const count = counts[level] || counts.normal
+    const palette = ['#FF6B35', '#FFD93D', '#4CAF50', '#2979FF', '#EC407A', '#7E57C2', '#FF8C5A', '#5C9CFF', '#6EC072', '#A08AD6']
+    const pieces = []
+    for (let i = 0; i < count; i++) {
+      pieces.push({
+        left: Math.round((i / count) * 96 + 2),
+        color: palette[i % palette.length],
+        delay: Math.round(Math.random() * 300) / 1000,
+        rotate: Math.round((Math.random() * 90) - 45),
+        size: level === 'first' ? 40 : level === 'milestone' ? 36 : 32
+      })
+    }
+    return pieces
+  },
+
   onUnload() {
     voice.stop()
     voice.destroy()

pages/timer/timer.wxml

@@ -2,16 +2,17 @@
 
   <!-- 全屏彩带完成庆祝 -->
   <view class="confetti" wx:if="{{isCompleted}}">
-    <view class="confetti-piece c1"></view>
-    <view class="confetti-piece c2"></view>
-    <view class="confetti-piece c3"></view>
-    <view class="confetti-piece c4"></view>
-    <view class="confetti-piece c5"></view>
-    <view class="confetti-piece c6"></view>
-    <view class="confetti-piece c7"></view>
-    <view class="confetti-piece c8"></view>
-    <view class="confetti-piece c9"></view>
-    <view class="confetti-piece c10"></view>
+    <view
+      wx:for="{{confettiPieces}}"
+      wx:key="i"
+      class="confetti-piece confetti-piece--{{celebrationLevel}}"
+      style="left: {{item.left}}%; background: {{item.color}}; animation-delay: {{item.delay}}s; transform: rotate({{item.rotate}}deg); width: {{item.size}}rpx; height: {{item.size * 2}}rpx;"
+    ></view>
+  </view>
+
+  <!-- 成就横幅 (record / milestone / first) -->
+  <view class="achievement-banner" wx:if="{{isCompleted && celebrationLevel !== 'normal'}}">
+    <text class="achievement-text">{{celebrationMessage}}</text>
   </view>
 
   <!-- 呼吸引导环 + 进度条 -->

pages/timer/timer.wxss

@@ -155,24 +155,56 @@
 .confetti-piece {
   position: absolute;
   top: -20rpx;
-  width: 16rpx;
-  height: 32rpx;
   border-radius: 4rpx;
   animation: confettiFall 2.4s ease-out forwards;
 }
 
-.c1  { left: 10%;  background: #FF6B35; animation-delay: 0.00s; transform: rotate(15deg); }
-.c2  { left: 22%;  background: #FFD93D; animation-delay: 0.10s; transform: rotate(-20deg); }
-.c3  { left: 34%;  background: #4CAF50; animation-delay: 0.20s; transform: rotate(30deg); }
-.c4  { left: 46%;  background: #2979FF; animation-delay: 0.05s; transform: rotate(-10deg); }
-.c5  { left: 58%;  background: #EC407A; animation-delay: 0.15s; transform: rotate(45deg); }
-.c6  { left: 70%;  background: #7E57C2; animation-delay: 0.25s; transform: rotate(-30deg); }
-.c7  { left: 82%;  background: #FF8C5A; animation-delay: 0.08s; transform: rotate(20deg); }
-.c8  { left: 14%;  background: #5C9CFF; animation-delay: 0.18s; transform: rotate(-40deg); }
-.c9  { left: 38%;  background: #6EC072; animation-delay: 0.28s; transform: rotate(50deg); }
-.c10 { left: 90%;  background: #FFD93D; animation-delay: 0.12s; transform: rotate(-25deg); }
+/* Higher celebration levels: faster / longer fall */
+.confetti-piece--milestone,
+.confetti-piece--first,
+.confetti-piece--record {
+  animation-duration: 3.2s;
+}
+
+.confetti-piece--first {
+  animation-duration: 4s;
+}
 
 @keyframes confettiFall {
   0%   { opacity: 1; transform: translateY(0) rotate(0deg); }
   100% { opacity: 0.6; transform: translateY(100vh) rotate(720deg); }
 }
+
+/* ---- achievement banner ---- */
+.achievement-banner {
+  position: fixed;
+  top: 160rpx;
+  left: 50%;
+  transform: translateX(-50%);
+  background: linear-gradient(135deg, var(--primary), var(--primary-light));
+  color: #FFFFFF;
+  font-size: 32rpx;
+  font-weight: 700;
+  padding: 24rpx 48rpx;
+  border-radius: 48rpx;
+  box-shadow: 0 8rpx 24rpx rgba(var(--primary-rgb), 0.4);
+  z-index: 10000;
+  animation: achievementIn 0.5s cubic-bezier(0.34, 1.56, 0.64, 1) both,
+             achievementOut 0.4s ease-in 3.5s both;
+  white-space: nowrap;
+}
+
+.achievement-text {
+  display: block;
+  line-height: 1;
+}
+
+@keyframes achievementIn {
+  0%   { opacity: 0; transform: translateX(-50%) scale(0.5); }
+  100% { opacity: 1; transform: translateX(-50%) scale(1); }
+}
+
+@keyframes achievementOut {
+  0%   { opacity: 1; transform: translateX(-50%) scale(1); }
+  100% { opacity: 0; transform: translateX(-50%) scale(0.8); }
+}