Folding Ribbon: Collapsed Indicators, Masking, Bracket Emphasis

[thecoolwinter]

Description

• Adjacent folds (folds that start/end on the same line) are drawn with a horizontal line instead of overlapping their pills.
• Collapsed folds are drawn with the correct indicator
  • This indicator does not respond to hovering
  • When a lower-depth fold is hovered, the collapsed indicator masks itself to that hovered fold's bounds. This creates a nice effect to avoid overlapping the hovered fold boundary and the collapsed box. The hovered fold's chevrons are also hidden if they overlap the collapsed fold.
  • When a collapsed indicator is clicked it toggles the fold.
• Adds an emphasis to hovered folds that have brackets surrounding their fold range.
  • @austincondiff may start working on a better emphasis style, so this is a placeholder for now just to indicate the functionality. It should be very easy to replace with the new style once it's done.

Related Issues

• almost rounds out ✨ Code Folding #43
• Requires Merge Trailing Line on Attachments, Select Attachments CodeEditTextView#98
• Requires Async and Faster Folding Calculation #331

Checklist

• I read and understood the contributing guide as well as the code of conduct
• The issues this PR addresses are related to each other
• My changes generate no new warnings
• My code builds and runs on my machine
• My changes are all related to the related issue above
• I documented my code

Screenshots

Screen.Recording.2025-06-06.at.10.57.01.AM.mov