✨ Show Code Structure when Scrolling (aka Sticky Headers)

### Description

When working in long source files, it's easy to lose track of which class, function, or structural block you're currently in while scrolling. A helpful enhancement would be to show a floating indicator or sticky header that displays the current code structure as you scroll through the file.

### Proposed Behavior

- While scrolling, a temporary overlay or sticky header appears, showing the current structural context (e.g., class, function, namespace).
- The indicator updates in real-time based on scroll position.
- The indicator fades out after scrolling stops or once the user re-engages with the editor.

### Implementation Notes

- We can leverage the existing Tree-sitter integration to identify and display the current structure based on the syntax tree.
- This could tie into the same symbol parsing used for outline views or breadcrumbs, minimizing duplication.

### Benefits

- Improves orientation when navigating large files.
- Reduces mental overhead by keeping context visible.
- Useful for both reading and editing code, especially in deeply nested files.

### Additional Context

This behavior would be especially valuable during code review, debugging, or when working in unfamiliar codebases. It could be made optional in preferences.

- https://twitter.com/a_grebenyuk/status/1534359760308424711?s=21&t=Ok1RPHZ0s8iMU6Bf3HYJyA
- https://learn.microsoft.com/en-us/visualstudio/ide/editor-sticky-scroll?view=vs-2022

## Screenshots

https://github.com/user-attachments/assets/36920923-bfd8-45f1-a63f-9b7873f4de6e