fix: address audit findings — fitting trigger, race guards, state conflicts

wear-check:
- Send weak pulse light (brightness=26) to trigger FFE4 fitting report
- Timeout degrades to pass (backward compat with 17-byte firmware)
- Sync _resolved flag prevents double-resolve

treating:
- Only treat run_state=0x00 as completion after seeing run_state=0x02
  (prevents false completion on startup)
- Sync _finishing flag replaces async data.completed for race prevention
- onStatus preserves paused state during fitting loss (|| fittingLost)
- Remove dead _fittingTimer reference from onUnload

auto-scan:
- Sync _completed flag in _scanComplete prevents double-build

miniprogram/pages/treating/treating.js

@@ -84,7 +84,6 @@ Page({
     if (this._onFitting) ble.off('fitting', this._onFitting)
     if (this._onRunState) ble.off('run_state', this._onRunState)
     if (this._localTimer) clearInterval(this._localTimer)
-    if (this._fittingTimer) clearTimeout(this._fittingTimer)
   },
 
   onFitting: function (data) {
@@ -99,10 +98,15 @@ Page({
   },
 
   onRunState: function (data) {
-    if (this.data.completed) return
+    if (this._finishing) return
     console.log('[TREAT] run_state:', data.run_state)
 
-    if (data.run_state === 0xFF) {
+    if (data.run_state === 0x02) {
+      this._seenTreating = true
+    }
+
+    if (data.run_state === 0xFF && !this._finishing) {
+      this._finishing = true
       this.setData({ deviceFault: true })
       var self = this
       wx.showModal({
@@ -114,7 +118,7 @@ Page({
       return
     }
 
-    if (data.run_state === 0x00 && !this.data.paused && !this.data.fittingLost) {
+    if (data.run_state === 0x00 && this._seenTreating && !this.data.fittingLost) {
       this.finishAsComplete()
     }
   },
@@ -170,7 +174,7 @@ Page({
     this.setData({
       battery: status.battery || this.data.battery,
       temperature: status.temperature || this.data.temperature,
-      paused: status.mode_state === 0x03
+      paused: status.mode_state === 0x03 || this.data.fittingLost
     })
     this.syncCommands()
   },
@@ -239,7 +243,8 @@ Page({
   },
 
   finishAsComplete: function () {
-    if (this.data.completed) return
+    if (this._finishing) return
+    this._finishing = true
     var elapsed = Math.min(this.data.duration, Date.now() - this.data.startedAt)
     this.syncTreatmentEnd(elapsed)
     this.onComplete({