fix: watchdog 누락 경로 수정 + 시작 로그 추가

- CCCD 없는 경로(no CCCD, no RX)에서도 startWatchdog() + startBatteryPolling() 호출
- watchdog 시작 시 WATCHDOG_STARTED 로그 기록 (실제 동작 확인용)

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

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

@@ -361,6 +361,7 @@ class BleManager private constructor(private val context: Context) {
         stopWatchdog()
         lastRxTimestamp = System.currentTimeMillis()
         watchdogRunning = true
+        debugLogger.info("WATCHDOG_STARTED timeout=${watchdogTimeoutMs}ms")
 
         watchdogJob = Thread({
             while (watchdogRunning) {
@@ -630,19 +631,21 @@ class BleManager private constructor(private val context: Context) {
                     }
                 } else {
                     logw { "CCCD descriptor not found for RX characteristic" }
-                    // No CCCD but still mark ready if characteristics exist
                     handler.post {
                         if (txCharacteristic != null && rxCharacteristic != null) {
                             isServiceReady.value = true
+                            startBatteryPolling()
+                            startWatchdog()
                             logd { "Service ready (no CCCD)" }
                         }
                     }
                 }
             } ?: run {
-                // No RX characteristic, mark ready if TX exists
                 handler.post {
                     if (txCharacteristic != null) {
                         isServiceReady.value = true
+                        startBatteryPolling()
+                        startWatchdog()
                         logd { "Service ready (no RX)" }
                     }
                 }