Fix in-window fullscreen exit behavior

[boweic]

Fixes in-window fullscreen behavior by allowing Esc to exit, preserving playback and page position, and removing Chrome MV3 manifest warnings.

Changes:

• Capture Escape in simulated fullscreen modes so in-window can exit like native fullscreen.
• Preserve page/video position when leaving simulated fullscreen.
• Restore playback if entering simulated fullscreen pauses a video that was already playing.
• Remove Chrome MV3 manifest warnings for unsupported keys.