feat: establish teaching feedback mini program

Connect student profiles, defaults, and feedback records to the Rust API. Configure the WeChat AppID, custom tab bar, and local development workflow for version 0.1.0.

custom-tab-bar/index.json

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+{
+  "component": true
+}

custom-tab-bar/index.ts

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+const tabItems = [
+  { pagePath: '/pages/feedback/index', text: '反馈生成', glyph: '✦' },
+  { pagePath: '/pages/students/index', text: '学生档案', glyph: '◎' },
+  { pagePath: '/pages/records/index', text: '反馈记录', glyph: '◴' },
+  { pagePath: '/pages/profile/index', text: '我的', glyph: '◉' }
+]
+
+Component({
+  data: {
+    selected: 0,
+    tabItems
+  },
+  methods: {
+    switchTab(event: WechatMiniprogram.TouchEvent) {
+      const { index, path } = event.currentTarget.dataset as { index: number; path: string }
+      if (!path) return
+      if (index === this.data.selected) return
+      this.setData({ selected: index })
+      wx.switchTab({ url: path })
+    }
+  }
+})

custom-tab-bar/index.wxml

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+<view class="tabbar" role="tablist">
+  <view
+    wx:for="{{tabItems}}"
+    wx:key="pagePath"
+    class="tab-item {{selected === index ? 'tab-item-active' : ''}}"
+    data-index="{{index}}"
+    data-path="{{item.pagePath}}"
+    bindtap="switchTab"
+    role="tab"
+  >
+    <text class="tab-glyph">{{item.glyph}}</text>
+    <text class="tab-label">{{item.text}}</text>
+  </view>
+</view>

custom-tab-bar/index.wxss

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+.tabbar {
+  position: fixed;
+  right: 0;
+  bottom: 0;
+  left: 0;
+  z-index: 100;
+  display: flex;
+  min-height: 112rpx;
+  padding-bottom: env(safe-area-inset-bottom);
+  border-top: 1rpx solid #edf1f6;
+  background: #ffffff;
+}
+
+.tab-item {
+  display: flex;
+  flex: 1;
+  flex-direction: column;
+  align-items: center;
+  justify-content: center;
+  gap: 6rpx;
+  min-height: 112rpx;
+  color: #8995a5;
+}
+
+.tab-item-active {
+  color: #2b67e8;
+}
+
+.tab-glyph {
+  font-size: 42rpx;
+  font-weight: 500;
+  line-height: 1;
+}
+
+.tab-label {
+  font-size: 24rpx;
+  line-height: 1.2;
+}