fix(android): remove device_info from joinSession to match Electron behavior

The server validates device_type and only accepts specific values.
Electron doesn't send device_info at all, which passes validation.
Match that behavior for consistency.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

backend/mpc-system/services/service-party-android/app/src/main/java/com/durian/tssparty/data/remote/GrpcClient.kt

@@ -90,18 +90,11 @@ class GrpcClient @Inject constructor() {
         joinToken: String
     ): Result<JoinSessionData> = withContext(Dispatchers.IO) {
         try {
-            val deviceInfo = DeviceInfo.newBuilder()
-                .setDeviceType("mobile")
-                .setDeviceId(partyId)
-                .setPlatform("android")
-                .setAppVersion("1.0.0")
-                .build()
-
+            // Match Electron behavior: don't send device_info
             val request = JoinSessionRequest.newBuilder()
                 .setSessionId(sessionId)
                 .setPartyId(partyId)
                 .setJoinToken(joinToken)
-                .setDeviceInfo(deviceInfo)
                 .build()
 
             val response = stub?.joinSession(request)