fix: allow Tab to reach visible find controls when collapsed

[cipheraxat]

Summary

• Tab from Find/Replace no longer always targets the case-sensitive toggle
• When find option toggles (or prev/next) are display: none under .collapsed-find-widget, focus advances to the next visible enabled control (Find in Selection / Close)
• Same visibility check applied to preserve-case → actions and Close → Replace paths

Fixes #280340

Root cause

Custom Tab handlers always called focusOnCaseSensitive() and preventDefault(). In the collapsed (narrow / non-maximized) layout those toggles are hidden, so Tab appeared to do nothing — especially painful with a screen reader.

Test plan

• Unit routing: expanded → caseSensitive; collapsed → selection; selection disabled → close
• Narrow the window until Find shows .collapsed-find-widget
• Ctrl/Cmd+F, press Tab — focus moves to Find in Selection or Close
• Ctrl/Cmd+H, Tab from replace — same, does not trap
• Maximize / widen — Tab still reaches case / whole-word / regex toggles
• Screen reader: Tab announces a real control after the find input

[Copilot]

Pull request overview

Fixes keyboard focus trapping in collapsed editor Find/Replace widgets.

Changes:

• Skips hidden or disabled controls during Tab navigation.
• Routes focus to the next visible action or back to the editor.