fix(desktop): make first-pinned-feed default actually take effect

Two bugs that together caused HomeFeed to always open on Following:

1. FeedScreen was reading feedRepo.pinnedFeeds.value as the source of
   truth for the first pinned feed. That's a stateIn-derived flow with
   initial value persistentListOf(); the underlying _feeds StateFlow
   IS loaded synchronously by FeedDefinitionRepository on construction,
   but the derived pinnedFeeds doesn't reflect it until the first flow
   emission propagates — which is too late for `remember` to see.
   Fixed by reading feedRepo.feeds.value directly and filtering /
   sorting by pinOrder ourselves.

2. DeckColumnContainer was passing initialFeedMode = FeedMode.FOLLOWING
   when rendering DeckColumnType.HomeFeed, which overrode FeedScreen's
   first-pinned logic entirely. Removed the hardcode so the deck's
   home column inherits FeedScreen's default.

With both fixed, a user who has only Global pinned now opens to Global
on launch instead of Following.

desktopApp/src/jvmMain/kotlin/com/vitorpamplona/amethyst/desktop/ui/FeedScreen.kt

@@ -436,7 +436,16 @@ fun FeedScreen(
     // not whatever DesktopPreferences happened to save last. If a caller
     // explicitly passes customFeedId/initialFeedMode, that always wins.
     val feedRepo = com.vitorpamplona.amethyst.desktop.ui.deck.LocalFeedRepository.current
-    val firstPinned = remember { feedRepo.pinnedFeeds.value.firstOrNull() }
+    // Read feeds.value (the source StateFlow that's loaded synchronously by
+    // FeedDefinitionRepository on construction) rather than pinnedFeeds.value —
+    // the latter is a stateIn-derived flow whose initial value is an empty list
+    // until the first flow emission propagates, which is too late for `remember`.
+    val firstPinned =
+        remember {
+            feedRepo.feeds.value
+                .filter { it.pinned }
+                .minByOrNull { it.pinOrder }
+        }
     val firstPinnedCustomSource = firstPinned?.source as? com.vitorpamplona.amethyst.commons.feeds.custom.FeedSource.Filter
 
     var activeFeedId by remember {

desktopApp/src/jvmMain/kotlin/com/vitorpamplona/amethyst/desktop/ui/deck/DeckColumnContainer.kt

@@ -327,6 +327,8 @@ internal fun RootContent(
 
     when (columnType) {
         DeckColumnType.HomeFeed -> {
+            // Don't hardcode initialFeedMode — let FeedScreen pick the first
+            // pinned feed (Following/Global/Custom) as the default tab.
             FeedScreen(
                 relayManager = relayManager,
                 localCache = localCache,
@@ -334,7 +336,6 @@ internal fun RootContent(
                 iAccount = iAccount,
                 nwcConnection = nwcConnection,
                 subscriptionsCoordinator = subscriptionsCoordinator,
-                initialFeedMode = FeedMode.FOLLOWING,
                 onCompose = onShowComposeDialog,
                 onNavigateToProfile = onNavigateToProfile,
                 onNavigateToThread = onNavigateToThread,