feat(studio): Fullscreen (F key) Distraction-Free Composition Preview #995

Problem

Currently, users cannot focus on their video composition without distractions from UI elements like the timeline, or sidebars. This makes it harder to preview or show a composition in an immersive, true-to-final state. There is no dedicated fullscreen mode for distraction-free review.

Proposed solution

Introduce a native fullscreen mode for compositions using the HTML5 Fullscreen API. This feature should be activated by pressing the F key (and exited with the Esc key). When in fullscreen:

• The composition takes over the screen, hiding all sidebars and UI except the composition itself.
• Keyboard shortcuts for playback and editing (spacebar, J/K/L, m, shift+L, I/O, shift+I/O, etc.) remain fully functional.
• The feature should behave consistently across browsers and local host usage, relying only on the native Fullscreen API.

Additional context

This would greatly improve demoing, reviewing, and focusing on creative work in Hyperframes. It matches the expectations of video editors and creative tools that support distraction-free modes. Keyboard shortcut summary:

• F: Enter fullscreen
• Esc: Exit fullscreen
• All other NLE shortcuts remain active in fullscreen.