fix: use seekable resource for seeks instead of refetching

[Akinori107]

Changes

Added seek support using createSeekeableAudioResource in _connectAndPlayStream, so it skips the full re-fetch/reconnect when seeking. Falls back to the old _fetchResource method if it fails or the source/protocol isn't supported (local, deezer, sabr, hls, dash)

Why

&t=X timestamps were always ignored, track just started from 0 regardless of position. It's actually worse than just "seek doesn't work" though, since track-end is scheduled based on trackLength - startPosition, the track gets cut off early too. e.g. seek to 1:43 on a 2:34 track and it'll stop around 0:51 of real playback, since the audio was actually playing from 0:00 the whole time.

Checkmarks

• The modified endpoints have been tested
• Used the same indentation as the rest of the project
• Still compatible with LavaLink clients

Additional information

tsc + biome pass

[github-actions]

All Contributors have signed the CLA. The PR is now allowed to be merged.
_{Posted by the CLA Assistant Lite bot.}

[Akinori107]

I have read the CLA Document and I hereby sign the CLA

[ToddyTheNoobDud]

Thanks for your contribuition! :)

[1Lucas1apk]

Thank you for finding and fixing the problem, eternally grateful ✨