init: 毛孩子计划 小程序 + Go 后端 + 内嵌后台

- pets-fe: 微信原生小程序（首页/计划/记录/报告/社区/引导），
  服务端驱动、无假数据；弹层改用 scroll-view，打开时隐藏自定义 tabBar
- pets-be: Gin + GORM(MySQL, sundynix_ 前缀) + MinIO，统一响应/分页，
  微信 code2session 登录，provider-neutral AI(DeepSeek)，go:embed React 后台
- 修复：分段选择类型不匹配（字符串 vs 数字）导致选不中

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

pets-fe/components/nav-bar/nav-bar.js

@@ -0,0 +1,31 @@
+const app = getApp();
+
+Component({
+  options: { addGlobalClass: true },
+  properties: {
+    title: { type: String, value: '毛孩子计划' },
+    showBack: { type: Boolean, value: false }
+  },
+  data: {
+    statusBarHeight: 20,
+    navBarHeight: 44
+  },
+  lifetimes: {
+    attached() {
+      this.setData({
+        statusBarHeight: app.globalData.statusBarHeight,
+        navBarHeight: app.globalData.navBarHeight
+      });
+    }
+  },
+  methods: {
+    onBack() {
+      const pages = getCurrentPages();
+      if (pages.length > 1) {
+        wx.navigateBack();
+      } else {
+        wx.switchTab({ url: '/pages/home/home' });
+      }
+    }
+  }
+});

pets-fe/components/nav-bar/nav-bar.json

@@ -0,0 +1,4 @@
+{
+  "component": true,
+  "usingComponents": {}
+}

pets-fe/components/nav-bar/nav-bar.wxml

@@ -0,0 +1,8 @@
+<view class="nav-wrap" style="padding-top:{{statusBarHeight}}px;height:{{statusBarHeight + navBarHeight}}px;">
+  <view class="nav-inner" style="height:{{navBarHeight}}px;">
+    <view wx:if="{{showBack}}" class="nav-back" bindtap="onBack">‹</view>
+    <view class="nav-title">{{title}}</view>
+  </view>
+</view>
+<!-- 占位，避免内容被固定导航栏遮挡 -->
+<view style="height:{{statusBarHeight + navBarHeight}}px;"></view>

pets-fe/components/nav-bar/nav-bar.wxss

@@ -0,0 +1,19 @@
+:host{display:block}
+.nav-wrap{
+  position:fixed;top:0;left:0;right:0;z-index:100;
+  background:rgba(248,246,242,.82);
+  backdrop-filter:blur(28rpx);
+  -webkit-backdrop-filter:blur(28rpx);
+}
+.nav-inner{
+  position:relative;display:flex;align-items:center;justify-content:center;
+}
+.nav-title{
+  font-size:32rpx;font-weight:900;color:var(--text);
+  max-width:60%;overflow:hidden;text-overflow:ellipsis;white-space:nowrap;
+}
+.nav-back{
+  position:absolute;left:20rpx;top:50%;transform:translateY(-50%);
+  width:64rpx;height:64rpx;display:flex;align-items:center;justify-content:center;
+  font-size:52rpx;line-height:1;color:var(--text);
+}