fix: keep initial playback focus off the titlebar pin

Restore the playback window as first responder after initial setup and after file/YouTube dialogs return. Keep native control focus indicators and Tab navigation unchanged.

Verified hidden native window focus, both dialog cancellations, explicit control focus, Tab navigation, P shortcut, app build, and compact-window checks.

README.md

@@ -53,6 +53,8 @@ Drag the compact video to move the window; on release, each axis snaps independe
 
 Single-key shortcuts apply only to the playback window and do not intercept text editing, file-picker input, or Command/Control/Option combinations. Held toggle keys do not repeatedly toggle; held `J`/`L` continue seeking and held `,`/`.` continue stepping. `C` captions remains unbound.
 
+Initial window setup and returning from the file/YouTube dialogs leave keyboard focus on playback rather than automatically highlighting the titlebar pin. Tab navigation and native focus indicators remain available when choosing controls explicitly.
+
 Frame stepping uses decoded presentation timestamps, not an average-FPS time offset, including variable-frame-rate video and reordered B-frames. Steps start from the displayed frame, stop at the first/last frame, and keep the timeline paused. Consecutive same-direction repeats share one counted queue entry without skipping frames or reordering seeks/direction changes. The last presented image remains visible during decoder preroll and queued steps; the progress thumb follows each authoritative stepped position. Opening/closing media still clears the old image. Audio-only files disable stepping; normal playback resumes with audio synchronized to the selected frame.
 
 - Existing shortcuts remain: **⌘O** opens files, **←/→** seeks five seconds, **↑/↓** adjusts volume by five percent, **⌃⌘F** toggles fullscreen, and **Esc** leaves fullscreen. Double-clicking normal-mode video also toggles fullscreen.