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/search/search.wxml

@@ -0,0 +1,26 @@
+<view class="page">
+  <navbar title="搜索" />
+  <view class="searchbar">
+    <view class="searchbar__box">
+      <text class="searchbar__icon">🔍</text>
+      <input
+        class="searchbar__input"
+        placeholder="搜索动作 / 器械 / 部位"
+        placeholder-class="ph"
+        value="{{q}}"
+        confirm-type="search"
+        bindinput="onInput" />
+    </view>
+  </view>
+
+  <view class="section" style="padding-top: 8rpx;">
+    <view class="grid" wx:if="{{results.length}}">
+      <view class="grid__item" wx:for="{{results}}" wx:key="id">
+        <exercise-card exercise="{{item}}" bind:tap="onExercise" />
+      </view>
+    </view>
+    <view wx:elif="{{loading}}" class="empty">搜索中…</view>
+    <view wx:elif="{{searched}}" class="empty">未找到相关动作</view>
+    <view wx:else class="empty">输入关键词开始搜索</view>
+  </view>
+</view>