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/components/navbar/index.wxml

@@ -0,0 +1,7 @@
+<view class="navbar">
+  <view class="navbar__status" style="height: {{statusBarHeight}}px;"></view>
+  <view class="navbar__bar">
+    <view wx:if="{{showBack}}" class="navbar__back" bindtap="onBack">‹</view>
+    <view wx:if="{{title}}" class="navbar__title">{{title}}</view>
+  </view>
+</view>