[Blackspirits]

Testing workstream only — fork-local draft PR; not intended for merge.

The branch combines three independently proposed changes on current upstream SubtitleEdit/subtitleedit@c0e7ac3e0ef97bcc1b6efdc24a995f7ea94e5909 solely to validate compilation, behavior and interactions in GitHub Actions:

1. Keep all edit-box action buttons visible when shrinking the splitter (regression cases: 2, 5 and 7 buttons).
2. Add Catppuccin Mocha and Dracula dark palettes and previews.
3. Use the active theme palette in ComboBox dropdowns and scrollbar tracks/thumbs (including System theme changes).

After green CI and review, create separate upstream PRs. Running CI is not a substitute for manual visual tests on Windows/macOS/Linux. Do not merge this CI-only branch.

[Blackspirits]

Superseded by fork-only CI Draft #172, reconstructed on the current upstream main commit 5e673e4 without overlapping upstream file changes. The new branch HEAD fb91bec4 passed all four Linux CI test jobs. This superseded PR is closed without merge to avoid duplicate review/CI branches; the new PR remains Draft, requires independent review and (for UI) Windows visual validation.