fix: BLE reconnect를 fresh scan→connect 방식으로 변경

기존: connectGatt(autoConnect=true) — Android에서 매우 불안정, 수분 걸림
변경: BLE 스캔으로 기기를 다시 찾은 후 connectGatt(autoConnect=false)로 빠르게 연결

재연결 흐름:
1. watchdog 15초 타임아웃 → forceDisconnectAndReconnect()
2. scheduleAutoReconnect() → 3s/5s/10s 백오프
3. attemptAutoReconnect():
   - BLE 스캔 시작 (기기 이름 or MAC 주소 매칭)
   - 발견 시 즉시 connectGatt(autoConnect=false) → 빠른 연결
   - 8초 스캔 타임아웃 → 다음 attempt
   - 최대 5회 시도 후 실패 처리
4. 모든 단계 BleDebugLogger에 기록

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

app/src/main/java/com/example/medilightv2android/ble/BleManager.kt

@@ -418,8 +418,11 @@ class BleManager private constructor(private val context: Context) {
         handler.postDelayed(timer, delay)
     }
 
+    private var reconnectScanCallback: ScanCallback? = null
+
     private fun attemptAutoReconnect() {
-        val address = lastConnectedAddress ?: return
+        val targetAddress = lastConnectedAddress ?: return
+        val targetName = debugLogger.deviceName
         if (bluetoothAdapter?.isEnabled != true) {
             onReconnectionFailed?.invoke()
             isReconnecting.value = false
@@ -427,15 +430,69 @@ class BleManager private constructor(private val context: Context) {
         }
 
         reconnectAttempt++
-        logd { "Attempting auto-reconnect #$reconnectAttempt to $address" }
+        logd { "Auto-reconnect #$reconnectAttempt: scanning for $targetName ($targetAddress)" }
+        debugLogger.info("RECONNECT_SCAN #$reconnectAttempt scanning for $targetName")
 
         bluetoothGatt?.let { gatt ->
             try { gatt.close() } catch (_: Exception) {}
             bluetoothGatt = null
         }
 
-        val device = bluetoothAdapter.getRemoteDevice(address)
-        bluetoothGatt = device.connectGatt(context, true, gattCallback, BluetoothDevice.TRANSPORT_LE)
+        // Fresh scan to find the device again
+        val scanner = bluetoothAdapter.bluetoothLeScanner
+        if (scanner == null) {
+            scheduleAutoReconnect()
+            return
+        }
+
+        // Stop any previous reconnect scan
+        reconnectScanCallback?.let {
+            try { scanner.stopScan(it) } catch (_: Exception) {}
+        }
+
+        val callback = object : ScanCallback() {
+            override fun onScanResult(callbackType: Int, result: ScanResult) {
+                val name = try { result.device.name ?: "" } catch (_: Exception) { "" }
+                val address = result.device.address
+
+                if (address == targetAddress || (targetName.isNotEmpty() && name == targetName)) {
+                    logd { "Reconnect scan found: $name ($address)" }
+                    debugLogger.info("RECONNECT_FOUND $name ($address) RSSI=${result.rssi}")
+
+                    try { scanner.stopScan(this) } catch (_: Exception) {}
+                    reconnectScanCallback = null
+
+                    // Connect directly (autoConnect=false for fast connection)
+                    bluetoothGatt = result.device.connectGatt(
+                        context, false, gattCallback, BluetoothDevice.TRANSPORT_LE
+                    )
+                }
+            }
+        }
+        reconnectScanCallback = callback
+
+        try {
+            scanner.startScan(callback)
+        } catch (e: Exception) {
+            debugLogger.error("RECONNECT_SCAN_FAIL ${e.message}")
+            scheduleAutoReconnect()
+            return
+        }
+
+        // Stop scan after 8 seconds → retry next attempt
+        handler.postDelayed({
+            try { scanner.stopScan(callback) } catch (_: Exception) {}
+            reconnectScanCallback = null
+
+            if (!isConnected.value && reconnectAttempt < maxReconnectAttempts) {
+                debugLogger.warn("RECONNECT_SCAN_TIMEOUT #$reconnectAttempt — device not found")
+                scheduleAutoReconnect()
+            } else if (!isConnected.value) {
+                debugLogger.reconnectFailed()
+                isReconnecting.value = false
+                onReconnectionFailed?.invoke()
+            }
+        }, 8000)
     }
 
     private fun cancelReconnectTimer() {