feat(#534): add OAuth provider management screen + credential_warning surfacing (#566)

* feat(#534): add OAuth provider management screen + credential_warning surfacing

* style(#534): fix ktlint import-ordering in ProvidersViewModel

* fix(#534): address agy review — terminal DONE/ERROR dialog states + PKCE browser launch

* fix(#534): add Done/Close dialog strings

* fix(#534): address agy review - terminal DONE/ERROR dialog states, real PKCE browser launch, clear flow state

---------

Co-authored-by: M57 <m57@hermes-control.app>

app/src/main/java/com/m57/hermescontrol/ui/chat/ChatScreen.kt

@@ -124,12 +124,15 @@ import com.m57.hermescontrol.R
 import com.m57.hermescontrol.data.model.Attachment
 import com.m57.hermescontrol.data.ws.CommandCatalog
 import com.m57.hermescontrol.data.ws.ConnectionStatus
+import com.m57.hermescontrol.data.ws.HermesWsClient
 import com.m57.hermescontrol.notification.NotificationHelper
 import com.m57.hermescontrol.theme.LocalHermesStatusColors
 import com.m57.hermescontrol.theme.StatusRed
+import com.m57.hermescontrol.ui.common.CredentialWarningBanner
 import com.m57.hermescontrol.ui.common.EmptyState
 import com.m57.hermescontrol.ui.common.HermesScaffold
 import com.m57.hermescontrol.ui.common.NavIcon
+import com.m57.hermescontrol.ui.providers.ProvidersScreen
 import kotlinx.coroutines.delay
 import kotlinx.coroutines.flow.collectLatest
 import kotlinx.coroutines.flow.distinctUntilChanged
@@ -151,6 +154,7 @@ fun ChatScreen(
 ) {
     val state by viewModel.uiState.collectAsStateWithLifecycle()
     val streamingState by viewModel.streamingState.collectAsStateWithLifecycle()
+    val credentialWarning by HermesWsClient.credentialWarning.collectAsStateWithLifecycle()
     val listState = rememberLazyListState()
     var isOlderPagingArmed by remember(state.currentSessionId) { mutableStateOf(false) }
 
@@ -403,6 +407,14 @@ fun ChatScreen(
                 onReloginClick = { showReloginDialog = true },
             )
 
+            credentialWarning?.let { warning ->
+                CredentialWarningBanner(
+                    warning = warning,
+                    onFix = { NavigationController.navigateTo(com.m57.hermescontrol.ProvidersScreen) },
+                    onDismiss = { HermesWsClient.clearCredentialWarning() },
+                )
+            }
+
             Box(
                 modifier =
                     Modifier