Wallper 1.3.3 — Mini Patch (Bugfix & UX)

• Apply button now shows MiniSpinner with fade/scale animation.
• Busy state propagated (FullscreenVideoView → FullscreenBottomBar).
• Button disables while busy to prevent duplicate actions.
• Auto-apply runs immediately after download completes.
• Minor transition tweaks for smoother, clearer feedback.