feat(desktop): branded loading screen instead of login flash on startup

- Add AccountState.Loading as initial state (was LoggedOut)
- Show centered "Amethyst" + spinner while accounts load from storage
- After loadSavedAccount(): transition to LoggedIn or LoggedOut
- No more 0.5s flash of login screen when account exists

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

desktopApp/src/jvmMain/kotlin/com/vitorpamplona/amethyst/desktop/Main.kt

@@ -32,6 +32,7 @@ import androidx.compose.foundation.layout.fillMaxWidth
 import androidx.compose.foundation.layout.height
 import androidx.compose.foundation.layout.heightIn
 import androidx.compose.foundation.layout.padding
+import androidx.compose.foundation.layout.size
 import androidx.compose.foundation.lazy.LazyColumn
 import androidx.compose.foundation.lazy.items
 import androidx.compose.foundation.rememberScrollState
@@ -864,6 +865,7 @@ fun App(
             }
 
             is AccountState.ConnectingRelays -> {}
+            is AccountState.Loading -> {}
         }
     }
 
@@ -924,8 +926,10 @@ fun App(
                 if (current != null) {
                     accountManager.loadNwcConnection(current.npub)
                 }
+            } else {
+                // No saved account found → show login screen
+                accountManager.setLoggedOut()
             }
-            // If failure: state remains LoggedOut → login screen shows automatically
         }
 
         onDispose {
@@ -956,6 +960,28 @@ fun App(
                     com.vitorpamplona.amethyst.desktop.ui.deck.LocalLocalRelayStore provides localRelayStore,
                 ) {
                     when (accountState) {
+                        is AccountState.Loading -> {
+                            // Branded loading screen while accounts load from storage
+                            Box(
+                                modifier = Modifier.fillMaxSize(),
+                                contentAlignment = Alignment.Center,
+                            ) {
+                                Column(horizontalAlignment = Alignment.CenterHorizontally) {
+                                    androidx.compose.material3.CircularProgressIndicator(
+                                        modifier = Modifier.size(32.dp),
+                                        color = MaterialTheme.colorScheme.primary,
+                                        strokeWidth = 3.dp,
+                                    )
+                                    Spacer(Modifier.height(16.dp))
+                                    Text(
+                                        "Amethyst",
+                                        style = MaterialTheme.typography.headlineMedium,
+                                        color = MaterialTheme.colorScheme.onBackground,
+                                    )
+                                }
+                            }
+                        }
+
                         is AccountState.LoggedOut -> {
                             LoginScreen(
                                 accountManager = accountManager,

desktopApp/src/jvmMain/kotlin/com/vitorpamplona/amethyst/desktop/account/AccountManager.kt

@@ -69,6 +69,8 @@ import kotlinx.coroutines.withTimeout
 import java.io.File
 
 sealed class AccountState {
+    data object Loading : AccountState()
+
     data object LoggedOut : AccountState()
 
     data object ConnectingRelays : AccountState()
@@ -123,7 +125,7 @@ class AccountManager internal constructor(
     private val _allAccounts = MutableStateFlow<ImmutableList<AccountInfo>>(persistentListOf())
     val allAccounts: StateFlow<ImmutableList<AccountInfo>> = _allAccounts.asStateFlow()
 
-    private val _accountState = MutableStateFlow<AccountState>(AccountState.LoggedOut)
+    private val _accountState = MutableStateFlow<AccountState>(AccountState.Loading)
     val accountState: StateFlow<AccountState> = _accountState.asStateFlow()
 
     private val _nwcConnection = MutableStateFlow<Nip47WalletConnect.Nip47URINorm?>(null)
@@ -463,6 +465,10 @@ class AccountManager internal constructor(
         accountStorage.setCurrentAccount(npub)
     }
 
+    fun setLoggedOut() {
+        _accountState.value = AccountState.LoggedOut
+    }
+
     fun setConnectingRelays() {
         _accountState.value = AccountState.ConnectingRelays
     }

desktopApp/src/jvmTest/kotlin/com/vitorpamplona/amethyst/desktop/account/AccountManagerStateTransitionTest.kt

@@ -94,12 +94,12 @@ class AccountManagerStateTransitionTest {
 
             advanceUntilIdle()
 
-            // Should see: LoggedOut → ConnectingRelays → LoggedIn
+            // Should see: Loading → ConnectingRelays → LoggedIn
             assertTrue(
                 states.size >= 3,
                 "Expected at least 3 state transitions, got ${states.size}: $states",
             )
-            assertIs<AccountState.LoggedOut>(states[0])
+            assertIs<AccountState.Loading>(states[0])
             assertIs<AccountState.ConnectingRelays>(states[1])
             assertIs<AccountState.LoggedIn>(states[2])
 
@@ -125,12 +125,12 @@ class AccountManagerStateTransitionTest {
 
             advanceUntilIdle()
 
-            // Should see: LoggedOut → ConnectingRelays → LoggedOut
+            // Should see: Loading → ConnectingRelays → LoggedOut
             assertTrue(
                 states.size >= 3,
                 "Expected at least 3 state transitions, got ${states.size}: $states",
             )
-            assertIs<AccountState.LoggedOut>(states[0])
+            assertIs<AccountState.Loading>(states[0])
             assertIs<AccountState.ConnectingRelays>(states[1])
             assertIs<AccountState.LoggedOut>(states[2])