feat: implement P0 security and reliability improvements

- bcrypt password hashing with auto-migration from SHA-256
- BLE command retry (3 attempts, 500ms delay, skip on disconnect)
- BLE auto-reconnect with service re-discovery on disconnect
- Treatment page disconnect/reconnect event handling
- Token refresh endpoint with 3-day grace period
- Client-side token auto-refresh when <24h remaining
- Single treatment record detail API with ownership check

miniprogram/pages/treating/treating.js

@@ -33,9 +33,15 @@ Page({
     this._onStatus = this.onStatus.bind(this)
     this._onComplete = this.onComplete.bind(this)
     this._onException = this.onException.bind(this)
+    this._onDisconnect = this.onDisconnect.bind(this)
+    this._onReconnect = this.onReconnect.bind(this)
+    this._onReconnectFailed = this.onReconnectFailed.bind(this)
     ble.on('status', this._onStatus)
     ble.on('treatment_complete', this._onComplete)
     ble.on('exception', this._onException)
+    ble.on('disconnected', this._onDisconnect)
+    ble.on('reconnected', this._onReconnect)
+    ble.on('reconnect_failed', this._onReconnectFailed)
     this.startLocalTimer()
     this.syncCommands()
   },
@@ -44,6 +50,9 @@ Page({
     if (this._onStatus) ble.off('status', this._onStatus)
     if (this._onComplete) ble.off('treatment_complete', this._onComplete)
     if (this._onException) ble.off('exception', this._onException)
+    if (this._onDisconnect) ble.off('disconnected', this._onDisconnect)
+    if (this._onReconnect) ble.off('reconnected', this._onReconnect)
+    if (this._onReconnectFailed) ble.off('reconnect_failed', this._onReconnectFailed)
     if (this._localTimer) clearInterval(this._localTimer)
   },
 
@@ -131,6 +140,40 @@ Page({
     })
   },
 
+  onDisconnect: function () {
+    this.setData({ paused: true })
+    wx.showToast({
+      title: '设备连接断开，正在重连...',
+      icon: 'none',
+      duration: 3000
+    })
+  },
+
+  onReconnect: function () {
+    this.setData({ paused: false })
+    wx.showToast({
+      title: '设备已重新连接',
+      icon: 'success',
+      duration: 2000
+    })
+  },
+
+  onReconnectFailed: function () {
+    var self = this
+    if (this._localTimer) {
+      clearInterval(this._localTimer)
+      this._localTimer = null
+    }
+    wx.showModal({
+      title: '连接丢失',
+      content: '设备蓝牙连接已断开，无法恢复。本次护理数据将保存。',
+      showCancel: false,
+      complete: function () {
+        self.finishAsComplete()
+      }
+    })
+  },
+
   onStop: function () {
     var self = this
     wx.showModal({