fix(feeds): offset PullToRefresh indicator below top bar

Inside a DisappearingScaffold the content fills the full screen height so
feeds can scroll behind the top bar. PullToRefreshBox anchors its indicator
at the top of the box, which placed it behind the top bar.

Read LocalDisappearingScaffoldPadding inside RefresheableBox and pass a
custom indicator with that top padding applied, so the spinner surfaces
just below the bar. Screens not inside a DisappearingScaffold see the
default 0dp padding and behave as before.

https://claude.ai/code/session_01MgnMaw8U83rXPSnoGF4KBY

amethyst/src/main/java/com/vitorpamplona/amethyst/ui/feeds/RefresheableBox.kt

@@ -23,15 +23,20 @@ package com.vitorpamplona.amethyst.ui.feeds
 import androidx.compose.foundation.layout.Box
 import androidx.compose.foundation.layout.BoxScope
 import androidx.compose.foundation.layout.fillMaxSize
+import androidx.compose.foundation.layout.padding
 import androidx.compose.material3.ExperimentalMaterial3Api
 import androidx.compose.material3.pulltorefresh.PullToRefreshBox
+import androidx.compose.material3.pulltorefresh.PullToRefreshDefaults
+import androidx.compose.material3.pulltorefresh.rememberPullToRefreshState
 import androidx.compose.runtime.Composable
 import androidx.compose.runtime.getValue
 import androidx.compose.runtime.mutableStateOf
 import androidx.compose.runtime.remember
 import androidx.compose.runtime.rememberCoroutineScope
 import androidx.compose.runtime.setValue
+import androidx.compose.ui.Alignment
 import androidx.compose.ui.Modifier
+import com.vitorpamplona.amethyst.ui.layouts.LocalDisappearingScaffoldPadding
 import kotlinx.coroutines.delay
 import kotlinx.coroutines.launch
 
@@ -54,10 +59,9 @@ fun RefresheableBox(
     }
 
     if (enablePullRefresh) {
-        PullToRefreshBox(
+        PullToRefreshBoxWithScaffoldPadding(
             isRefreshing = isRefreshing,
             onRefresh = onRefresh,
-            modifier = Modifier.fillMaxSize(),
             content = content,
         )
     } else {
@@ -82,10 +86,45 @@ fun RefresheableBox(
         }
     }
 
-    PullToRefreshBox(
+    PullToRefreshBoxWithScaffoldPadding(
         isRefreshing = isRefreshing,
         onRefresh = onRefreshWrapped,
-        modifier = Modifier.fillMaxSize(),
+        content = content,
+    )
+}
+
+/**
+ * [PullToRefreshBox] anchors its indicator at the top of the box. Inside a
+ * [DisappearingScaffold] the content fills the full screen height (feed items
+ * scroll behind the top bar), so the default indicator would appear behind the
+ * top bar. Offset the indicator down by the scaffold's top padding so it
+ * surfaces just below the bar.
+ */
+@OptIn(ExperimentalMaterial3Api::class)
+@Composable
+private fun PullToRefreshBoxWithScaffoldPadding(
+    isRefreshing: Boolean,
+    onRefresh: () -> Unit,
+    content: @Composable BoxScope.() -> Unit,
+) {
+    val state = rememberPullToRefreshState()
+    val topPadding = LocalDisappearingScaffoldPadding.current.calculateTopPadding()
+
+    PullToRefreshBox(
+        isRefreshing = isRefreshing,
+        onRefresh = onRefresh,
+        state = state,
+        modifier = Modifier.fillMaxSize(),
+        indicator = {
+            PullToRefreshDefaults.Indicator(
+                modifier =
+                    Modifier
+                        .align(Alignment.TopCenter)
+                        .padding(top = topPadding),
+                isRefreshing = isRefreshing,
+                state = state,
+            )
+        },
         content = content,
     )
 }