feat: add guest mode and optimize login experience

针对微信审核要求新增游客浏览模式，用户可无需登录直接浏览应用内容，仅在使用发布、点赞、记录等需要身份的功能时才弹窗引导登录。具体修改包括：
1. 新增游客态判断工具函数与登录守卫逻辑
2. 为登录页添加游客直接进入入口
3. 为首页、酒友圈、个人页、动态页、记录页添加游客适配逻辑
4. 优化登录态失效处理逻辑，不再强制跳转登录页
5. 调整部分页面的返回逻辑适配分享直接进入场景
6. 为各页面添加游客引导UI与交互

pages/index/index.vue

@@ -8,6 +8,15 @@
       </view>
     </view>
 
+    <!-- 游客登录引导条（非阻断，可继续浏览；登录由用户自行选择） -->
+    <view v-if="isGuest" class="guest-banner" @click="goLogin">
+      <view class="guest-banner-info">
+        <text class="guest-banner-title">登录后开启完整记录</text>
+        <text class="guest-banner-desc">云端同步 · 成就徽章 · 酒友互动</text>
+      </view>
+      <text class="guest-banner-btn">去登录</text>
+    </view>
+
     <!-- 核心CTA - 首页最醒目位置 -->
     <view class="hero-cta" @click="goRecord">
       <view class="hero-cta-bg"></view>
@@ -139,7 +148,7 @@
 
 <script>
 import DrinkCalendar from '../../components/DrinkCalendar.vue'
-import client from '../../common/api'
+import client, { isLoggedIn, requireLogin } from '../../common/api'
 import { GetCalendarReq, DeleteRecordReq, CreateRecordReq, GetRecordDetailReq } from 'HaveADrink'
 import { getGreeting, formatDate, getWeekStart, getCatIcon, isIconPath, calcLocalStreak } from '../../common/utils'
 import { FEELINGS, DRINK_CATEGORIES, DRINK_UNITS } from '../../common/constants'
@@ -196,6 +205,13 @@ export default {
     if (isFirst === 'true') {
       return
     }
+    // 游客可直接浏览首页：不发起鉴权请求，展示空数据；
+    // 仅在用户主动点击记录等功能时才引导登录（微信审核要求：先浏览后登录）
+    this.isGuest = !isLoggedIn()
+    if (this.isGuest) {
+      this.initGuestView()
+      return
+    }
     this.loadData()
   },
   onShareAppMessage() {
@@ -211,6 +227,26 @@ export default {
     }
   },
   methods: {
+    // 游客浏览视图：问候语与零数据，页面结构可完整浏览，不发起任何鉴权请求
+    initGuestView() {
+      this.greeting = getGreeting()
+      this.userName = '酒友'
+      this.records = []
+      this.stats = {
+        weekDrinkCount: 0,
+        weekCups: 0,
+        monthDrinkCount: 0,
+        monthCups: 0,
+        streak: 0,
+        streakType: 'drank',
+        drankStreak: 0,
+        abstainStreak: 0
+      }
+    },
+    // 游客主动点击"去登录"
+    goLogin() {
+      uni.navigateTo({ url: '/pages/login/login' })
+    },
     async loadData() {
       this.greeting = getGreeting()
       // 并行加载用户信息、统计概览、记录列表
@@ -436,14 +472,17 @@ export default {
       })
     },
     goRecord() {
+      if (!requireLogin()) return
       uni.navigateTo({ url: '/pages/record/record' })
     },
     goRecordToday() {
+      if (!requireLogin()) return
       this.showDayDetail = false
       uni.navigateTo({ url: '/pages/record/record' })
     },
     // 标记为未饮酒（直接创建 abstain 记录）
     async markAbstain() {
+      if (!requireLogin()) return
       const recordData = {
         date: this.selectedDate,
         mode: 'abstain',
@@ -497,6 +536,49 @@ export default {
   margin-top: 4rpx;
 }
 
+/* 游客登录引导条（非阻断） */
+.guest-banner {
+  display: flex;
+  align-items: center;
+  justify-content: space-between;
+  padding: $sp-md $sp-lg;
+  margin-bottom: $sp-md;
+  border-radius: $radius-lg;
+  background: rgba(232, 168, 56, 0.08);
+  border: 2rpx solid rgba(232, 168, 56, 0.25);
+
+  &:active {
+    background: rgba(232, 168, 56, 0.14);
+  }
+}
+
+.guest-banner-info {
+  display: flex;
+  flex-direction: column;
+  gap: 4rpx;
+}
+
+.guest-banner-title {
+  font-size: $fs-sm;
+  font-weight: $fw-bold;
+  color: $amber;
+}
+
+.guest-banner-desc {
+  font-size: $fs-xs;
+  color: $text-tertiary;
+}
+
+.guest-banner-btn {
+  font-size: $fs-sm;
+  font-weight: $fw-bold;
+  color: $text-on-amber;
+  background: linear-gradient(135deg, $amber-light, $amber-deep);
+  padding: $sp-xs $sp-lg;
+  border-radius: $radius-full;
+  flex-shrink: 0;
+}
+
 .calendar-section {
   margin-bottom: $sp-md;
   padding: $sp-md;