[Feature Request] Missing playback selectors: audio track and subtitle selection for videos

Immich's video player currently has no way to choose an audio track or subtitle track. Containers such as MKV (and also MP4, MOV, WebM) often include multiple audio streams (languages, commentary, etc.) and several subtitle streams. Right now only the default one can be heard or seen, and the other streams are inaccessible from the UI. Problem When a video has several audio tracks, there is no selector, so the user can't switch to another language or commentary track. Embedded subtitles (SRT, ASS/SSA, PGS, WebVTT, mov_text) can't be enabled, disabled, or switched. This makes Immich less useful for people who also store movies, shows, travel videos, or recordings with multiple tracks in their library, and forces them to open an external player. Proposed solution Add two selectors to the video player controls (web and mobile): Audio track selector Lists all audio streams in the file, showing language and title metadata when available (e.g. "English – 5.1"…