merge: upstream/experimental with citations feature

- Merge upstream changes including image search, tooltips, and UI improvements
- Keep citations feature with inline hover cards
- Resolve conflict in message-list-item.tsx: use upstream img max-width (90%) while preserving citations logic
- Maintain file upload improvements with citations support

Co-authored-by: Cursor <cursoragent@cursor.com>

frontend/src/components/workspace/messages/message-list-item.tsx

@@ -243,7 +243,7 @@ function MessageContent_({
               if (typeof src !== "string") {
                 return (
                   <img
-                    className="max-w-full overflow-hidden rounded-lg"
+                    className="max-w-[90%] overflow-hidden rounded-lg"
                     src={src}
                     alt={alt}
                   />
@@ -256,7 +256,7 @@ function MessageContent_({
               return (
                 <a href={url} target="_blank" rel="noopener noreferrer">
                   <img
-                    className="max-w-full overflow-hidden rounded-lg"
+                    className="max-w-[90%] overflow-hidden rounded-lg"
                     src={url}
                     alt={alt}
                   />