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.

pages/feedback/index.wxml

@@ -0,0 +1,46 @@
+<view class="page-shell feedback-page">
+  <text class="eyebrow">课堂反馈</text>
+  <view class="page-heading">
+    <text class="heading-icon">✦</text>
+    <text class="page-title">反馈生成</text>
+  </view>
+  <text class="page-subtitle">填写课堂表现并保存到教学反馈记录。</text>
+
+  <view wx:if="{{errorMessage}}" class="status-banner">
+    <text>{{errorMessage}}</text>
+    <text class="status-action" bindtap="retryLoad">重试</text>
+  </view>
+
+  <view class="feedback-form surface">
+    <picker class="feedback-field" mode="selector" range="{{profileOptions}}" value="{{selectedProfileIndex}}" disabled="{{loading}}" bindchange="onProfileChange">
+      <text class="form-label">学生档案</text>
+      <text class="form-value">{{loading ? '正在加载...' : profileOptions[selectedProfileIndex]}}</text>
+    </picker>
+
+    <picker class="feedback-field" mode="date" value="{{draft.feedbackDate}}" bindchange="onDateChange">
+      <text class="form-label">反馈日期</text>
+      <text class="form-value">{{draft.feedbackDate}}</text>
+    </picker>
+
+    <view class="content-field">
+      <view class="content-label-row">
+        <text class="form-label">反馈内容</text>
+        <text class="content-count">{{contentLength}} / 2000</text>
+      </view>
+      <textarea
+        class="feedback-textarea"
+        value="{{draft.content}}"
+        maxlength="2000"
+        placeholder="记录课堂完成情况、进步与后续建议"
+        bindinput="onContentInput"
+      />
+    </view>
+
+    <button class="save-feedback primary-button" loading="{{saving}}" disabled="{{saving}}" bindtap="saveFeedback">保存反馈</button>
+  </view>
+
+  <view wx:if="{{!loading && profiles.length === 0}}" class="profiles-hint">
+    <text>当前没有学生档案，反馈仍可不关联学生直接保存。</text>
+    <text class="status-action" bindtap="goStudents">新建档案</text>
+  </view>
+</view>