Add manual button and keyboard shortcut to force HDMI handshake / renegotiation

[haxman]

Is your feature request related to a problem? Please describe.
While you stated that the auto-detection and HDMI handshake handling are being developed, the video signal occasionally needs to be re-initialized when switching modes, resolutions, or changing source profiles (e.g., via scalers like the RetroTINK 4K Pro). Currently, recovering from a lost or mismatched signal often requires restarting the application or reloading the driver.

Describe the solution you'd like
A manual trigger in EverLive to force a new HDMI handshake / hotplug renegotiation between the Host (GC573 capture card) and the Source device.

Specifically:

1. UI Button: A button on the EverLive toolbar/interface (e.g., "Reset Handshake" / "HDMI Re-sync").
2. Keyboard Shortcut: A dedicated shortcut key (e.g., H or R) to trigger the renegotiation directly without having to navigate menus.

Describe alternatives you've considered
Restarting ./play.sh or reloading the kernel module via script every time a handshake stalls or fails to latch onto a new resolution/sync rate.

Additional context
Having an explicit hotplug/handshake reset trigger is also extremely helpful for troubleshooting non-standard refresh rates, resolution changes (e.g., 240p/480i to 480p), and EDID latching issues during development.

[Everlite]

Hi @haxman,

Thank you for this suggestion! This is a great addition for troubleshooting and on-the-fly resolution or mode changes.

Implemented in Commit c1af212:

1. Header Deck Toolbar Button: Added a dedicated "🔄 Re-Sync" button directly on the EverLive Studio toolbar next to the Stream Toggle button.
2. Keyboard Shortcuts: Added H and R shortcut triggers across both the GUI app and the standalone everlive_display engine:
   • In everlive_viewer.py, pressing H or R triggers hardware HDMI DV timing renegotiation via V4L2 and restarts the stream pipeline seamlessly.
   • In standalone everlive_display, pressing H or R queries hardware DV timings, re-applies them to the device, and flashes an on-screen "HDMI RE-SYNC" toast.

Documented in the README controls and bottom toolbar hints. Enjoy testing!

[haxman]

Thanks