Add aspect ratio selector to video player

[4in4in]

What

Adds an aspect ratio selector to the main video player, next to the existing resize mode (FIT/FILL/ZOOM) button.

• Auto (default) — use the video's own aspect ratio
• 1:1, 4:3, 16:9, 18:9, 21:9 — force a fixed ratio
• Custom… — dialog accepting 16:9, 16/9 or decimal 1.78 input

Why

Some videos are uploaded with wrong proportions (typically old 4:3 content stretched to 16:9, or anamorphic video without proper metadata). The resize modes can't fix that — they change how the video fits the screen, not the picture's own proportions. Forcing the correct ratio is the only way to watch such videos undistorted. VLC and MX Player offer the same control.

Behavior details

• The choice is per-video: it resets to Auto when playback moves to a different stream. A forced ratio is a correction for a specific broken video, so it intentionally doesn't persist (avoids the "why is everything stretched now" trap).
• Quality changes of the same stream do not reset the choice (the reset hooks into onMetadataChanged, which only fires when the stream URL actually changes).
• Vertical-video detection and screen rotation still use the stream's natural dimensions.
• The button is hidden in the popup player, same as the resize mode button.

[InfinityLoop1308]

Thanks. The feature is a good addition, but I think there is a UI semantics issue here.

The aspect ratio selector should be part of the same menu as the existing resize mode selector. In the
current design, if resize mode is set to Fill, the selected aspect ratio has no effect, which is misleading.

I would recommend keeping a single display-mode menu:

• Fit / Fill / Zoom, as before
• 1:1 / 4:3 / ... / Custom, newly added

When one of the aspect-ratio entries is selected, the player should apply that ratio with resize mode set to
Fit.

The reset strategy can remain the same: last_resize_mode still persists, while the forced aspect ratio
resets per video as proposed.

[4in4in]

Thanks for the review — makes sense, fixed.

There's now a single display-mode menu opened from the resize button, no separate control:

Fit / Fill / Zoom
──────────
1:1 / 4:3 / 16:9 / 18:9 / 21:9 / Custom…

• Selecting an aspect ratio applies it with resize mode set to Fit, so it can never silently have no effect.
• Selecting a resize mode clears any forced ratio.
• Reset strategy as you suggested: last_resize_mode persists; the forced aspect ratio is per-video. The Fit forced by a ratio is transient (not persisted), so the saved resize mode is restored on the next video.

Also added a divider between the two groups and a checkmark on the currently active entry.