fix(lefu): 完善蓝牙连接状态处理，修复断开后 UI 不同步问题

- connectState 回调增加 UNAVAILABLE 清理和 READY 自动重连
- disconnect() 增加 _intentionalConnect 标记避免误重连
- deviceWillDisconnect 增加 _activeProtocol 防重入判断
- connectedDevice/equipment/connectedWifi 增加断开状态响应
- connectedWifi 设备断开后自动退出配网页

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

miniprogram/pages/connectedWifi/connectedWifi.ts

@@ -25,7 +25,7 @@ Page({
     _toBleStatus(state: string): BleStatus {
         const bs = lefuService.BLUE_STATE
         if (state === bs.CONNECTSUCCESS || state === bs.WIFISUCCESS) return 'connected'
-        if (state === bs.CONNECTFAILED) return 'failed'
+        if (state === bs.CONNECTFAILED || state === bs.UNAVAILABLE) return 'failed'
         return 'connecting'
     },
 
@@ -34,6 +34,11 @@ Page({
         lefuService.onDeviceInfo((info) => {
             this.setData({ deviceName: info.modelNumber })
         })
+        // 设备断开即退出配网页
+        lefuService.onDisconnected(() => {
+            wx.showToast({ title: '设备已断开连接', icon: 'none', duration: 1500 })
+            setTimeout(() => wx.navigateBack(), 1500)
+        })
         this.setData({
             bleStatus: this._toBleStatus(lefuService.connectState),
             deviceName: lefuService.deviceInfo?.modelNumber ?? '智能体重秤',
@@ -43,15 +48,13 @@ Page({
 
     onShow() {
         lefuService.onConnectState((state) => {
-            const bs = lefuService.BLUE_STATE
-            if (state === bs.CONNECTSUCCESS || state === bs.WIFISUCCESS || state === bs.CONNECTFAILED) {
-                this.setData({ bleStatus: this._toBleStatus(state) })
-            }
+            this.setData({ bleStatus: this._toBleStatus(state) })
         })
     },
 
     onUnload() {
         wx.hideLoading()
+        lefuService.onDisconnected(() => {})
         if (this.data.status === 'configuring') {
             lefuService.disconnect()
         }