Add fullscreen crop mode toggle (hotkey c)

- In fullscreen, press 'c' to toggle object-fit between contain (default)
  and fill (stretches to fill, no aspect ratio preservation).
- Adds .player.crop-mode video { object-fit: fill; } in player.css.
- Adds toggleCrop() in player.js that toggles a crop-mode class and a
  small UI indicator (✂️) in the controls, visible only in fullscreen.
- Resets crop mode back to contain when exiting fullscreen (via Escape,
  minimize, or fullscreenchange event).
- Wires the 'c' hotkey in keyboard.js and registers toggleCrop in app.js.
- Adds crop-indicator to index.html and detach.html controls, and
  documents the shortcut in the help modal.

1 files changed, 2 insertions, 1 deletions

diff --git a/web/js/app.js b/web/js/app.js
index 9c769c9..13cc824 100644
--- a/web/js/app.js
+++ b/web/js/app.js
@@ -1,7 +1,7 @@
 import { API } from './api.js';
 import { initKeyboard } from './keyboard.js';
 import { initSelection, clearSelection, select, selectByElement, next, prev, currentIndex, currentElement, navUp, navDown, navLeft, navRight } from './selection.js';
-import { initPlayer, togglePlay, toggleFullscreen, toggleMinimize, toggleDetach, exitFullscreenIfNeeded, currentMediaId, currentMediaInfo, hasLoadedMedia, isPlaybackActive, seekRelative, selectAndPlay, zoomIn as playerZoomIn, zoomOut as playerZoomOut, toggleSlideshow as playerToggleSlideshow, isImageMode as playerIsImageMode } from './player.js';
+import { initPlayer, togglePlay, toggleFullscreen, toggleMinimize, toggleDetach, exitFullscreenIfNeeded, toggleCrop, currentMediaId, currentMediaInfo, hasLoadedMedia, isPlaybackActive, seekRelative, selectAndPlay, zoomIn as playerZoomIn, zoomOut as playerZoomOut, toggleSlideshow as playerToggleSlideshow, isImageMode as playerIsImageMode } from './player.js';
 import { initSearch, focusSearch, trigger as triggerSearch, parseQuery } from './search.js';
 import { initShuffle, toggle as toggleShuffle, isOn as isShuffle } from './shuffle.js';
 import { initThemes } from './themes.js';
@@ -134,6 +134,7 @@ async function initApp() {
     mediaInfo: () => toggleMediaInfo(),
     fullscreen: () => toggleFullscreen(),
     toggleMinimize: () => toggleMinimize(),
+    toggleCrop: () => toggleCrop(),
     escape: () => { exitFullscreenIfNeeded(); closeLightbox(); const el = currentElement(); if (el) el.classList.remove('selected'); closeAllModals(); },
     shuffle: () => { toggleShuffle(); loadMedia(); },
     share: () => shareSelected(),