perf: optimize startup, database, and ui rendering (#405)

* perf: optimize startup, database, and ui rendering

* fix(#405): address code review feedback

* test: wait for async prefs initialization to prevent coroutine leaks

* test: stub mockViewModel.streamingState in ChatScreenTest to prevent ClassCastException on Android

app/src/test/java/com/m57/hermescontrol/data/ws/HermesWsClientTest.kt

@@ -42,6 +42,7 @@ class HermesWsClientTest {
         mockkObject(AuthManager)
         every { AuthManager.wsUrl() } returns mockWebServer.url("/").toString().replace("http://", "ws://")
         every { AuthManager.isAutoReconnect() } returns false
+        every { AuthManager.getSessionCookie() } returns null
 
         // Reset state
         val connectedField = HermesWsClient::class.java.getDeclaredField("connected")