feat: add BleRelayManager sendRelayCommand and disconnect

android/app/src/main/java/com/eddy/atomrelay/BleRelayManager.kt

@@ -142,8 +142,29 @@ class BleRelayManager(
         handler.removeCallbacksAndMessages(null)
     }
 
-    fun sendRelayCommand(cmd: Byte) {}
-    fun disconnect() {}
+    @SuppressLint("MissingPermission")
+    fun sendRelayCommand(cmd: Byte) {
+        val char = relayCharacteristic ?: return
+        val gatt = bluetoothGatt ?: return
+        val key = hmacKey ?: return
+
+        val packet = buildPacket(cmd, key)
+        char.value = packet
+        char.writeType = BluetoothGattCharacteristic.WRITE_TYPE_NO_RESPONSE
+        gatt.writeCharacteristic(char)
+        seq++
+        if (seq > PrefsHelper.SEQ_MAX) seq = 1
+        PrefsHelper.getPrefs(context).edit().putInt(PrefsHelper.PREF_SEQ, seq).apply()
+        Log.d(TAG, "Sent relay cmd 0x${cmd.toString(16)} (seq=${seq - 1})")
+    }
+
+    @SuppressLint("MissingPermission")
+    fun disconnect() {
+        handler.removeCallbacks(scanRunnable)
+        scanTimeoutRunnable?.let { handler.removeCallbacks(it) }
+        stopScan()
+        bluetoothGatt?.disconnect()
+    }
     fun updateKeys() {
         loadState()
     }