Audio effect feature built in the video-core player

[Mouthieu]

Summary

Added an audio-effect extension (more of an equalizer) for the video-core player for online streaming.
I made sure to make it easy to configure and added only few changes on existing files.

AI disclosure

I used Gemini to generate a satisfying frontend that would fit the existing UI

Visualization when no sound is playing (basically when the player is paused)

Visualization when you can change the gains on-the-fly.

I also used chatGPT for a bunch of other debugging problems that I had (along with Gemini) but I didn't use them for the backend part.

~: Regarding the tests, I honestly did not really understand the whole testing architecture, I was just changing the values of my equalizer and listening to the changes directly.

Just a little disclaimer concerning these lines :

import { atomWithStorage } from "jotai/utils"
export const vc_eqGains = atomWithStorage<number[]>("vc_eq_gains", noneGains)

I don't know if you already have existing ways to keep some stuff in memory but that's kind of a trick that I used, tell me if there is something better to implement.

Checklist

• I have read CONTRIBUTING.md
• I set up Seanime locally.
• I understand the code I changed.
• I tested the change locally.
• I wrote this PR description myself.
• I disclosed any AI assistance.
• I can explain and maintain this change.