fix: expanded hunk corrupts line number display in gutter #697
Description
Summary
When inline diff hunk is expanded (click on diff marker), the line number for the expanded line shows garbled text (e.g., "87℃" instead of "37"). The hunk toolbar appears correctly, but the gutter line number is corrupted.
Screenshot
Line 37 shows "87℃" with the hunk toolbar visible on the right.
Motivation
Line numbers must always be readable, even when hunk viewer is expanded.
Implementation ideas
- The expanded hunk likely inserts content that shifts line number rendering
- Line number view may need to skip or specially handle expanded hunk lines
- Ensure LineNumberGutter accounts for expanded state