feat(plan): 新增「加入计划」选择器页 + 增强官方计划浏览，修复返回不刷新

1) 新增 pages/plan-select（加入我的计划选择器，替换详情页 actionSheet）
   - 默认展示我全部计划（浏览，不再强制搜索），支持 最近创建/动作最多 排序 + 名称搜索
   - 点选即把动作加入该计划并返回；无计划时引导新建
   - 入口接在 detail 页「加入计划」(无 planId 时 navigate 至此)
2) 增强 pages/collection（官方训练计划）
   - 默认展示全部分级，新增 等级筛选 chips + 名称搜索（均用现有字段，不改后端）
   - 筛选/搜索纯前端，viewGroups 驱动渲染
3) 修复 plan-detail 从「添加动作」返回后列表不刷新（上轮已单独提交 7ff55a6）
4) app.json 注册 plan-select 页面

miniprogram/pages/collection/collection.js

@@ -1,10 +1,15 @@
 const app = getApp();
 const planSvc = require('../../services/plan');
 
+// 官方训练计划浏览：默认展示全部分级，支持按等级筛选 + 名称搜索（均用现有字段）。
 Page({
   data: {
     statusBarHeight: 20,
     groups: [],
+    viewGroups: [],
+    levels: [{ value: 'all', label: '全部' }],
+    filterLevel: 'all',
+    keyword: '',
     loading: true
   },
 
@@ -15,20 +20,44 @@ Page({
 
   onShow() {
     // 从详情返回（可能收藏/导入变化）时刷新
-    if (!this.data.loading) this.load();
+    if (!this.data.loading && !this.data.keyword && this.data.filterLevel === 'all') this.load();
   },
 
   load() {
     this.setData({ loading: true });
     planSvc.officialGroups().then((res) => {
-      this.setData({ groups: (res && res.groups) || [], loading: false });
+      const groups = (res && res.groups) || [];
+      const levels = [{ value: 'all', label: '全部' }].concat(
+        groups.map((g) => ({ value: g.level, label: g.label }))
+      );
+      this.setData({ groups, levels, loading: false });
+      this.applyFilter();
     }).catch(() => {
-      this.setData({ groups: [], loading: false });
+      this.setData({ groups: [], viewGroups: [], levels: [{ value: 'all', label: '全部' }], loading: false });
     });
   },
 
-  // 计算某计划的跳转地址（供 wxml 使用）
-  planTarget(slug) {
-    return '/pages/collection-detail/collection-detail?slug=' + encodeURIComponent(slug);
+  applyFilter() {
+    const f = this.data.filterLevel;
+    const k = (this.data.keyword || '').trim().toLowerCase();
+    let groups = (this.data.groups || []).slice();
+    if (f !== 'all') groups = groups.filter((g) => g.level === f);
+    if (k) {
+      groups = groups
+        .map((g) => ({
+          ...g,
+          plans: (g.plans || []).filter((p) => (p.name || '').toLowerCase().includes(k))
+        }))
+        .filter((g) => (g.plans || []).length);
+    }
+    this.setData({ viewGroups: groups });
+  },
+
+  onFilter(e) {
+    this.setData({ filterLevel: e.detail.value }, () => this.applyFilter());
+  },
+
+  onSearch(e) {
+    this.setData({ keyword: e.detail.value }, () => this.applyFilter());
   }
 });

miniprogram/pages/collection/collection.json

@@ -3,6 +3,8 @@
   "usingComponents": {
     "navbar": "/components/navbar/index",
     "section-header": "/components/section-header/index",
-    "plan-card": "/components/plan-card/index"
+    "plan-card": "/components/plan-card/index",
+    "chip": "/components/chip/index",
+    "fc-icon": "/components/fc-icon/index"
   }
 }

miniprogram/pages/collection/collection.wxml

@@ -8,8 +8,33 @@
       <view class="intro__sub">从新手入门到高级挑战，分级规划你的每一次进阶</view>
     </view>
 
-    <block wx:if="{{groups.length}}">
-      <view class="group" wx:for="{{groups}}" wx:for-item="g" wx:key="level">
+    <view class="filterbar">
+      <scroll-view scroll-x class="filterbar__scroll">
+        <chip
+          wx:for="{{levels}}"
+          wx:key="value"
+          label="{{item.label}}"
+          value="{{item.value}}"
+          active="{{filterLevel === item.value}}"
+          bind:select="onFilter" />
+      </scroll-view>
+    </view>
+
+    <view class="searchbar">
+      <view class="searchbar__box">
+        <fc-icon name="search" size="28" color="var(--text-2)" />
+        <input
+          class="searchbar__input"
+          placeholder="搜索计划名称"
+          placeholder-class="ph"
+          value="{{keyword}}"
+          confirm-type="search"
+          bindinput="onSearch" />
+      </view>
+    </view>
+
+    <block wx:if="{{viewGroups.length}}">
+      <view class="group" wx:for="{{viewGroups}}" wx:for-item="g" wx:key="level">
         <section-header eyebrow="LEVEL" title="{{g.label}}" />
         <view class="grid">
           <view class="grid__item" wx:for="{{g.plans}}" wx:for-item="p" wx:key="slug">
@@ -21,7 +46,7 @@
       </view>
     </block>
 
-    <view wx:elif="{{!loading}}" class="empty">暂无官方计划</view>
+    <view wx:elif="{{!loading}}" class="empty">没有匹配的计划</view>
     <view wx:else class="empty">加载中…</view>
   </view>
 

miniprogram/pages/collection/collection.wxss

@@ -8,4 +8,17 @@
 .group + .group { margin-top: 36rpx; }
 .grid { display: flex; flex-wrap: wrap; gap: 18rpx; }
 .grid__item { width: calc((100% - 18rpx) / 2); }
+
+.filterbar { padding: 16rpx 32rpx 4rpx; }
+.filterbar__scroll { white-space: nowrap; }
+
+.searchbar { padding: 12rpx 32rpx; }
+.searchbar__box {
+  display: flex; align-items: center;
+  background: var(--surface); border: 1rpx solid var(--line);
+  border-radius: 999rpx; padding: 20rpx 28rpx;
+}
+.searchbar__input { flex: 1; color: var(--text); font-size: 28rpx; }
+.ph { color: var(--text-3); }
+
 .empty { color: var(--text-3); font-size: 26rpx; text-align: center; padding: 80rpx 0; }