feat: complete feature gaps across all modules

Server:
- Add settings-cache with 60s TTL for feature toggle checks
- Enforce maintenance_mode on login, enable_binding on device bind

Admin console:
- Remove dead "发送通知" button from user detail
- Firmware check calls real API and compares versions

Miniprogram:
- Wear-check: dynamic battery/connected from BLE state
- Login: hide non-functional phone auth button
- Treating: show actual selected regions instead of hardcoded "全脸"
- Index: display subscription status with tap to manage
- Auto-scan: show "待检测" instead of "--" for PD data
- Agreements: tap shows "内容建设中" modal

miniprogram/pages/treating/treating.js

@@ -18,19 +18,32 @@ Page({
     completed: false,
     startedAt: 0,
     devMode: false,
+    regionText: '全脸护理',
+  },
+
+  _getRegionText: function (regionMask) {
+    var REGION_MAP = {1:'左脸', 2:'右脸', 4:'额头', 8:'下巴', 16:'鼻', 32:'左眼', 64:'右眼'}
+    if (regionMask === 0x7F) return '全脸护理'
+    var names = []
+    for (var bit in REGION_MAP) {
+      if (regionMask & parseInt(bit)) names.push(REGION_MAP[bit])
+    }
+    return names.length > 0 ? names.join('+') + '护理' : '全脸护理'
   },
 
   onLoad: function (options) {
     var app = getApp()
     this.setData({ statusBarHeight: app.globalData.statusBarHeight, devMode: config.__DEV__ || false })
     this._deviceId = ble.getDeviceId() || (app.globalData.currentDevice && app.globalData.currentDevice.device_id) || ''
+    var regions = parseInt(options.regions) || 0x7F
     this.setData({
-      regions: parseInt(options.regions) || 0x7F,
+      regions: regions,
       wavelength: parseInt(options.wavelength) || 2,
       duration: parseInt(options.duration) || 600000,
       mode: parseInt(options.mode) || 0,
       remainingMs: parseInt(options.duration) || 600000,
-      startedAt: Date.now()
+      startedAt: Date.now(),
+      regionText: this._getRegionText(regions)
     })
 
     this._onStatus = this.onStatus.bind(this)

miniprogram/pages/treating/treating.wxml

@@ -16,7 +16,7 @@
     </view>
 
     <view class="mode-tag-area">
-      <text class="mode-tag">{{mode === 1 ? '✨ 智能模式' : '🔄 普通模式'}} · 全脸护理</text>
+      <text class="mode-tag">{{mode === 1 ? '✨ 智能模式' : '🔄 普通模式'}} · {{regionText}}</text>
     </view>
 
     <view class="relax-card">