fix(chats): drop scaffold top inset for inner feed in two-pane

In MessagesSinglePane the MessagesTabHeader sits inside the
DisappearingScaffold's topBar slot, so LocalDisappearingScaffoldPadding's
top component already covers the bar + tabs and the inner LazyColumn's
contentPadding lines the first row up flush below the tabs.

In MessagesTwoPane the tabs are part of the column content rather than
the scaffold's top slot. The scaffold still publishes its top-app-bar
height as the top inset, so rememberFeedContentPadding inside the feed
double-counts it and renders a top-app-bar-tall gap between the TabRow
and the first chatroom row.

Override LocalDisappearingScaffoldPadding around MessagesPager to zero
the top component while preserving start/end/bottom, so the feed still
clears the bottom bar.

amethyst/src/main/java/com/vitorpamplona/amethyst/ui/screen/loggedIn/chats/rooms/twopane/ChatroomListPane.kt

@@ -21,15 +21,22 @@
 package com.vitorpamplona.amethyst.ui.screen.loggedIn.chats.rooms.twopane
 
 import androidx.compose.foundation.layout.Column
+import androidx.compose.foundation.layout.PaddingValues
+import androidx.compose.foundation.layout.calculateEndPadding
+import androidx.compose.foundation.layout.calculateStartPadding
 import androidx.compose.foundation.pager.rememberPagerState
 import androidx.compose.runtime.Composable
+import androidx.compose.runtime.CompositionLocalProvider
 import androidx.compose.runtime.derivedStateOf
 import androidx.compose.runtime.getValue
 import androidx.compose.runtime.remember
+import androidx.compose.ui.platform.LocalLayoutDirection
+import androidx.compose.ui.unit.dp
 import com.vitorpamplona.amethyst.R
 import com.vitorpamplona.amethyst.commons.ui.feeds.FeedContentState
 import com.vitorpamplona.amethyst.ui.feeds.ScrollStateKeys
 import com.vitorpamplona.amethyst.ui.feeds.WatchLifecycleAndUpdateModel
+import com.vitorpamplona.amethyst.ui.layouts.LocalDisappearingScaffoldPadding
 import com.vitorpamplona.amethyst.ui.navigation.navs.INav
 import com.vitorpamplona.amethyst.ui.screen.loggedIn.AccountViewModel
 import com.vitorpamplona.amethyst.ui.screen.loggedIn.chats.rooms.datasource.ChatroomListFilterAssemblerSubscription
@@ -62,6 +69,25 @@ fun ChatroomList(
             }
         }
 
+    // The outer DisappearingScaffold publishes its top-app-bar height through
+    // LocalDisappearingScaffoldPadding so single-pane feeds can clear the bar via
+    // rememberFeedContentPadding. In the two-pane layout the tabs sit inside the
+    // column (not the scaffold's top slot), so the inner LazyColumn must not add
+    // that top inset again — otherwise it shows up as a gap below the TabRow.
+    // Drop only the top component; keep start/end/bottom so feeds still clear
+    // the bottom bar.
+    val outerScaffoldPadding = LocalDisappearingScaffoldPadding.current
+    val layoutDirection = LocalLayoutDirection.current
+    val innerScaffoldPadding =
+        remember(outerScaffoldPadding, layoutDirection) {
+            PaddingValues(
+                start = outerScaffoldPadding.calculateStartPadding(layoutDirection),
+                top = 0.dp,
+                end = outerScaffoldPadding.calculateEndPadding(layoutDirection),
+                bottom = outerScaffoldPadding.calculateBottomPadding(),
+            )
+        }
+
     Column {
         MessagesTabHeader(
             pagerState,
@@ -70,11 +96,13 @@ fun ChatroomList(
             { accountViewModel.markAllChatNotesAsRead(newFeedContentState.visibleNotes()) },
         )
 
-        MessagesPager(
-            pagerState,
-            tabs,
-            accountViewModel,
-            nav,
-        )
+        CompositionLocalProvider(LocalDisappearingScaffoldPadding provides innerScaffoldPadding) {
+            MessagesPager(
+                pagerState,
+                tabs,
+                accountViewModel,
+                nav,
+            )
+        }
     }
 }