feat(ui): mobile UX improvements, comment attachments, and cost breakdown

Add PWA meta tags for iOS home screen. Fix mobile properties drawer with safe
area insets. Add image attachment button to comment thread. Improve sidebar
with collapsible sections, project grouping, and mobile bottom nav. Show
token and billing type breakdown on costs page. Fix inbox loading state to
show content progressively. Various mobile overflow and layout fixes.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

ui/src/pages/Inbox.tsx

@@ -326,12 +326,12 @@ export function Inbox() {
     showStaleSection ? "stale_work" : null,
   ].filter((key): key is SectionKey => key !== null);
 
-  const isLoading =
-    isJoinRequestsLoading ||
-    isApprovalsLoading ||
-    isDashboardLoading ||
-    isIssuesLoading ||
-    isRunsLoading;
+  const allLoaded =
+    !isJoinRequestsLoading &&
+    !isApprovalsLoading &&
+    !isDashboardLoading &&
+    !isIssuesLoading &&
+    !isRunsLoading;
 
   const showSeparatorBefore = (key: SectionKey) => visibleSections.indexOf(key) > 0;
 
@@ -397,11 +397,14 @@ export function Inbox() {
         )}
       </div>
 
-      {isLoading && <p className="text-sm text-muted-foreground">Loading...</p>}
       {approvalsError && <p className="text-sm text-destructive">{approvalsError.message}</p>}
       {actionError && <p className="text-sm text-destructive">{actionError}</p>}
 
-      {!isLoading && visibleSections.length === 0 && (
+      {!allLoaded && visibleSections.length === 0 && (
+        <p className="text-sm text-muted-foreground">Loading...</p>
+      )}
+
+      {allLoaded && visibleSections.length === 0 && (
         <EmptyState
           icon={InboxIcon}
           message={tab === "new" ? "You're all caught up!" : "No inbox items match these filters."}