Load complete chat history when reaching the top (#2481)

* fix(chat): load older timeline history consistently

Pagination depended on scroll events, so short or compacted initial pages could never request older history. Reevaluate edge visibility as layout and history change, and standardize loading indicators on the canonical app spinner.

* fix(chat): keep older history loading reliably

Use authoritative timeline cursor progress so merged rows cannot stall pagination. Wait for bottom anchoring before evaluating the history edge, and re-arm retries on a fresh upward gesture without automatic failure loops.

packages/app/src/components/sidebar-workspace-list.tsx

@@ -1,8 +1,8 @@
+import { LoadingSpinner } from "@/components/ui/loading-spinner";
 import {
   View,
   Text,
   Pressable,
-  ActivityIndicator,
   ScrollView,
   type GestureResponderEvent,
   type PressableStateCallbackType,
@@ -143,7 +143,7 @@ const DEFAULT_STATUS_DOT_OFFSET = 0;
 const EMPHASIZED_STATUS_DOT_OFFSET = -1;
 const ThemedExternalLink = withUnistyles(ExternalLink);
 const ThemedGitPullRequest = withUnistyles(GitPullRequest);
-const ThemedActivityIndicator = withUnistyles(ActivityIndicator);
+const ThemedLoadingSpinner = withUnistyles(LoadingSpinner);
 const ThemedCircleAlert = withUnistyles(CircleAlert);
 const ThemedSyncedLoader = withUnistyles(SyncedLoader);
 const ThemedPlus = withUnistyles(Plus);
@@ -746,7 +746,7 @@ function ProjectLeadingVisualStatus({
   if (isArchiving) {
     return (
       <View style={styles.projectLeadingVisualSlot}>
-        <ThemedActivityIndicator size={8} uniProps={foregroundMutedColorMapping} />
+        <ThemedLoadingSpinner size={8} uniProps={foregroundMutedColorMapping} />
       </View>
     );
   }
@@ -855,7 +855,7 @@ function NewWorktreeButton({
           >
             {({ hovered, pressed }) =>
               loading ? (
-                <ThemedActivityIndicator size={14} uniProps={foregroundMutedColorMapping} />
+                <ThemedLoadingSpinner size={14} uniProps={foregroundMutedColorMapping} />
               ) : (
                 <ThemedPlus
                   size={15}