Use framework session bridges for Agent transport

Co-authored-by: Codex <noreply@openai.com>

android/app/src/main/java/com/openai/codexd/MainActivity.kt

@@ -94,7 +94,6 @@ class MainActivity : Activity() {
 
     override fun onCreate(savedInstanceState: Bundle?) {
         super.onCreate(savedInstanceState)
-        AgentSocketBridgeServer.ensureStarted(this)
         setContentView(R.layout.activity_main)
         updatePaths()
         handleSessionIntent(intent)