Improve performance, layout, and internal consistency across wallpaper UI and logic

[Kasper24]

• chore: cancel previous workflow runs for same branch or PR

  • Added GitHub Actions concurrency group to CI workflow
  • Ensures only the latest run for a branch or pull request is executed

• refactor: integrate react-virtualized for performant wallpaper grid rendering

  • Added react-virtualized and corresponding types for virtualized list
    rendering
  • Replaced CSS-based infinite scroll with Grid from
    react-virtualized for better performance
  • Implemented dynamic column/row calculation based on container size
  • Added auto-resize and lazy-loading via fetchNextPage on scroll
  • Updated styles to improve scrollbar appearance and grid responsiveness
  • Removed infiniteScrollRef logic in favor of onSectionRendered

• refactor: unify pagination and default query behavior across providers

  • Replaced limit with perPage in wallpaper.search schema for
    consistency
  • Set default query to "wallpaper" if empty for Pexels, Unsplash
  • Added default values for perPage in Pexels, Unsplash, and Wallpaper
    Engine routes
  • Removed redundant fallback logic in API request building
  • Adjusted frontend calls to omit limit where unnecessary

• fix: move apply button inside scroll area for better layout behavior

  • Shifted DialogFooter inside ScrollArea to ensure proper spacing
    and consistent scroll behavior.
  • Adjusted padding to align content more cleanly.

• fix: update setting key for lastWallpaperCmd to use internal namespace

  • Changed theme.lastWallpaperCmd to internal.lastWallpaperCmd when
    setting wallpaper engine command

• refactor: add detached param to execute

• refactor(dialogs): simplify DialogContent layout and adjust DialogFooter spacing

  • Removed explicit max-width/height constraints from
    ApplyWallpaperDialog
  • Moved DialogFooter outside ScrollArea for cleaner layout
  • Updated WallpaperDialog to remove redundant width constraints