feat: init fitness-coach (backend + miniprogram)

- backend: NestJS service with exercise/plan data
- miniprogram: WeChat mini program client
- exclude node_modules, dist, runtime data-store, local env

miniprogram/pages/detail/detail.wxml

@@ -0,0 +1,72 @@
+<view class="page" wx:if="{{exercise}}">
+  <navbar title="{{exercise.name}}" show-back />
+
+  <view class="hero">
+    <image
+      wx:if="{{exercise.gifUrl || exercise.image}}"
+      class="hero__img"
+      src="{{exercise.gifUrl || exercise.image}}"
+      mode="aspectFill" />
+    <view wx:else class="hero__ph">🏋️</view>
+  </view>
+
+  <view class="body section">
+    <view class="name">{{exercise.name}}</view>
+
+    <view class="metas">
+      <view class="meta"><view class="meta__k">部位</view><view class="meta__v">{{exercise.bodyPartLabel}}</view></view>
+      <view class="meta"><view class="meta__k">器械</view><view class="meta__v">{{exercise.equipmentLabel}}</view></view>
+      <view class="meta"><view class="meta__k">目标</view><view class="meta__v gold-text">{{exercise.targetLabel}}</view></view>
+      <view class="meta"><view class="meta__k">类型</view><view class="meta__v">{{exercise.typeLabel}}</view></view>
+    </view>
+
+    <view class="block" wx:if="{{exercise.muscleGroupLabel}}">
+      <view class="block__h eyebrow">主要肌群</view>
+      <view class="chips">
+        <text class="tag tag--gold">{{exercise.muscleGroupLabel}}</text>
+      </view>
+    </view>
+
+    <view class="block" wx:if="{{exercise.secondaryMusclesLabels.length}}">
+      <view class="block__h eyebrow">协同肌群</view>
+      <view class="chips">
+        <text wx:for="{{exercise.secondaryMusclesLabels}}" wx:key="*this" class="tag">{{item}}</text>
+      </view>
+    </view>
+
+    <view class="block" wx:if="{{exercise.instructionSteps.zh.length}}">
+      <view class="block__h eyebrow">动作步骤</view>
+      <view class="steps">
+        <view class="step" wx:for="{{exercise.instructionSteps.zh}}" wx:key="index">
+          <view class="step__n">{{index + 1}}</view>
+          <view class="step__t">{{item}}</view>
+        </view>
+      </view>
+    </view>
+
+    <view class="block" wx:if="{{exercise.instructions.zh}}">
+      <view class="block__h eyebrow">要点提示</view>
+      <view class="tips">{{exercise.instructions.zh}}</view>
+    </view>
+  </view>
+
+  <view class="section" wx:if="{{related.length}}">
+    <view class="block__h eyebrow">相关推荐</view>
+    <scroll-view scroll-x class="hscroll">
+      <view class="hscroll__item" wx:for="{{related}}" wx:key="id">
+        <exercise-card exercise="{{item}}" compact bind:tap="onExercise" />
+      </view>
+    </scroll-view>
+  </view>
+
+  <view class="addbar">
+    <view class="cta" bindtap="onAdd">加入今日训练</view>
+  </view>
+</view>
+
+<view wx:else class="empty-page">
+  <view class="topbar" style="padding-top: {{statusBarHeight}}px;">
+    <view class="topbar__back" bindtap="onBack">‹</view>
+  </view>
+  <view class="empty">{{ loading ? '加载中…' : '未找到该动作' }}</view>
+</view>