fix(home-banner): float DVM status banner over the feed instead of in the top bar

Putting HomeDvmStatusBanner inside the top-bar Column meant the
SecondaryTabRow shifted up/down every time the banner appeared or
disappeared (filter selection, refresh, response arrival). Annoying.

Move the banner into a Box that wraps the HorizontalPager and align
it to TopCenter so it floats over the feed:
- topBar Column is back to just HomeTopBar + SecondaryTabRow; tabs
  no longer reflow when the banner toggles.
- BannerCard takes a Modifier and gets tonalElevation + shadowElevation
  + a slightly stronger surface tint so it reads as a floating overlay
  rather than part of the scaffold chrome.

amethyst/src/main/java/com/vitorpamplona/amethyst/ui/screen/loggedIn/home/DvmStatusBanner.kt

@@ -58,13 +58,14 @@ import com.vitorpamplona.quartz.nip89AppHandlers.definition.AppDefinitionEvent
 fun HomeDvmStatusBanner(
     accountViewModel: AccountViewModel,
     nav: INav,
+    modifier: Modifier = Modifier,
 ) {
     val topFilter by accountViewModel.account.settings.defaultHomeFollowList
         .collectAsStateWithLifecycle()
 
     when (val filter = topFilter) {
-        is TopFilter.FavoriteDvm -> SingleDvmBanner(filter, accountViewModel, nav)
-        is TopFilter.AllFavoriteDvms -> AllFavoriteDvmsBanner(accountViewModel)
+        is TopFilter.FavoriteDvm -> SingleDvmBanner(filter, accountViewModel, nav, modifier)
+        is TopFilter.AllFavoriteDvms -> AllFavoriteDvmsBanner(accountViewModel, modifier)
         else -> Unit
     }
 }
@@ -74,6 +75,7 @@ private fun SingleDvmBanner(
     favDvm: TopFilter.FavoriteDvm,
     accountViewModel: AccountViewModel,
     nav: INav,
+    modifier: Modifier = Modifier,
 ) {
     val snapshot by accountViewModel.account.favoriteDvmOrchestrator
         .observe(favDvm.address)
@@ -95,7 +97,7 @@ private fun SingleDvmBanner(
                     ?: ""
             }
 
-        BannerCard {
+        BannerCard(modifier) {
             val status = snapshot.latestStatus?.status()
 
             when {
@@ -167,7 +169,10 @@ private fun SingleDvmBanner(
 }
 
 @Composable
-private fun AllFavoriteDvmsBanner(accountViewModel: AccountViewModel) {
+private fun AllFavoriteDvmsBanner(
+    accountViewModel: AccountViewModel,
+    modifier: Modifier = Modifier,
+) {
     val addresses by accountViewModel.account.favoriteDvmList.flow
         .collectAsStateWithLifecycle()
 
@@ -189,7 +194,7 @@ private fun AllFavoriteDvmsBanner(accountViewModel: AccountViewModel) {
 
     val allErrored = snapshots.all { it.errorMessage != null || it.latestStatus?.status()?.code == "error" }
 
-    BannerCard {
+    BannerCard(modifier) {
         if (allErrored) {
             BannerMessageRow(
                 message = stringRes(R.string.dvm_home_status_error),
@@ -209,14 +214,22 @@ private fun AllFavoriteDvmsBanner(accountViewModel: AccountViewModel) {
 }
 
 @Composable
-private fun BannerCard(content: @Composable () -> Unit) {
+private fun BannerCard(
+    modifier: Modifier = Modifier,
+    content: @Composable () -> Unit,
+) {
+    // Sits above the feed instead of in the topBar Column, so adding/removing
+    // the banner doesn't shift the tabs/filter up and down. tonalElevation
+    // gives it a faint surface tint so it reads as a floating overlay.
     Surface(
         modifier =
-            Modifier
+            modifier
                 .fillMaxWidth()
                 .padding(horizontal = 12.dp, vertical = 6.dp),
         shape = RoundedCornerShape(12.dp),
-        color = MaterialTheme.colorScheme.surfaceContainerLow,
+        color = MaterialTheme.colorScheme.surfaceContainerHigh,
+        tonalElevation = 4.dp,
+        shadowElevation = 4.dp,
     ) {
         Column(modifier = Modifier.padding(12.dp)) { content() }
     }

amethyst/src/main/java/com/vitorpamplona/amethyst/ui/screen/loggedIn/home/HomeScreen.kt

@@ -23,11 +23,14 @@ package com.vitorpamplona.amethyst.ui.screen.loggedIn.home
 import androidx.compose.foundation.ExperimentalFoundationApi
 import androidx.compose.foundation.layout.Arrangement
 import androidx.compose.foundation.layout.Arrangement.Absolute.spacedBy
+import androidx.compose.foundation.layout.Box
 import androidx.compose.foundation.layout.Column
+import androidx.compose.foundation.layout.PaddingValues
 import androidx.compose.foundation.layout.Row
 import androidx.compose.foundation.layout.Spacer
 import androidx.compose.foundation.layout.fillMaxSize
 import androidx.compose.foundation.layout.fillMaxWidth
+import androidx.compose.foundation.layout.padding
 import androidx.compose.foundation.lazy.LazyColumn
 import androidx.compose.foundation.lazy.LazyListState
 import androidx.compose.foundation.lazy.LazyRow
@@ -52,6 +55,7 @@ import androidx.compose.ui.Alignment
 import androidx.compose.ui.Modifier
 import androidx.compose.ui.graphics.Color
 import androidx.compose.ui.tooling.preview.Preview
+import androidx.compose.ui.unit.dp
 import androidx.lifecycle.compose.collectAsStateWithLifecycle
 import com.vitorpamplona.amethyst.Amethyst
 import com.vitorpamplona.amethyst.R
@@ -179,7 +183,6 @@ private fun HomePages(
         topBar = {
             Column {
                 HomeTopBar(accountViewModel, nav)
-                HomeDvmStatusBanner(accountViewModel, nav)
                 SecondaryTabRow(
                     containerColor = Color.Transparent,
                     contentColor = MaterialTheme.colorScheme.onBackground,
@@ -210,24 +213,37 @@ private fun HomePages(
             HomeScreenFloatingButton(accountViewModel, nav)
         },
         accountViewModel = accountViewModel,
-    ) {
-        HorizontalPager(
-            contentPadding = it,
-            state = pagerState,
-            userScrollEnabled = true,
-            modifier =
-                Modifier.zonedDrawerSwipe(
-                    pagerState = pagerState,
-                    openDrawer = nav::openDrawer,
-                ),
-        ) { page ->
-            HomeFeeds(
-                feedState = tabs[page].feedState,
-                routeForLastRead = tabs[page].routeForLastRead,
-                scrollStateKey = tabs[page].scrollStateKey,
-                liveSection = tabs[page].liveSection,
+    ) { paddingValues ->
+        // Wrap pager + banner in a Box so the banner can float over the feed
+        // (anchored top-center) instead of living in the topBar Column where
+        // it would push the tabs down every time it appears or disappears.
+        Box(
+            modifier = Modifier.fillMaxSize().padding(paddingValues),
+        ) {
+            HorizontalPager(
+                contentPadding = PaddingValues(0.dp),
+                state = pagerState,
+                userScrollEnabled = true,
+                modifier =
+                    Modifier.zonedDrawerSwipe(
+                        pagerState = pagerState,
+                        openDrawer = nav::openDrawer,
+                    ),
+            ) { page ->
+                HomeFeeds(
+                    feedState = tabs[page].feedState,
+                    routeForLastRead = tabs[page].routeForLastRead,
+                    scrollStateKey = tabs[page].scrollStateKey,
+                    liveSection = tabs[page].liveSection,
+                    accountViewModel = accountViewModel,
+                    nav = nav,
+                )
+            }
+
+            HomeDvmStatusBanner(
                 accountViewModel = accountViewModel,
                 nav = nav,
+                modifier = Modifier.align(Alignment.TopCenter),
             )
         }
     }