tweak(metronome): 三档位拍数统一改为 2 拍

慢走/健走/快走 三档 accent 从 4 → 2:
- 走路场景天然是左-右双脚交替的 2 拍循环
- 重音落在每一步的"主脚"(默认左脚),节奏感更贴合步态
- 4 拍听感像跑步进行曲,2 拍才是健走/慢跑实际节奏

需要 3/4 拍号的可在右下角微调里手动切换。

Co-authored-by: Cursor <cursoragent@cursor.com>

TUICallKit-Vue3/training/pages/metronome.vue

@@ -115,7 +115,7 @@ const PRESETS = [
         icon: '🚶',
         name: '慢走',
         bpm: 80,
-        accent: 4,
+        accent: 2,
         desc: '热身 · 恢复',
     },
     {
@@ -123,7 +123,7 @@ const PRESETS = [
         icon: '🏃‍♀️',
         name: '健走',
         bpm: 110,
-        accent: 4,
+        accent: 2,
         desc: '日常 · 通勤',
     },
     {
@@ -131,7 +131,7 @@ const PRESETS = [
         icon: '🏃',
         name: '快走',
         bpm: 130,
-        accent: 4,
+        accent: 2,
         desc: '提速 · 燃脂',
     },
 ] as const