Feature: upgrade thumbnail quality

[fire332]

This PR adds an option to upgrade the quality of thumbnail images that is disabled by default. It doesn't upgrade thumbnails for shorts or if it's from an A/B test (I'm not sure A/B test thumbnails even have a higher quality than hqdefault).

It works by detecting thumbnail elements, parsing their URLs from their background-image inline style, rewriting the URL to use a higher quality version & with WebP if supported, loading the image in the background, and finally swapping the images out if it loads successfully.

This PR is built on top of #235. That should be merged before this one. Re-based changes onto main.

Fixes #175, fixes #196, fixes #231

[fire332]

Thank you! Will this be in the next release or how do I install this fix onto my 0.3.4 version? (Newbie question I know!)

With Node.js 22 LTS installed:

• Use git to clone my fork on this branch, or download it here and extract it.
• Open the folder in terminal and run these commands:
  1. npm install
  2. npm run build && npm run package
  3. Use webOS Dev Manager to install the .ipk file.

[FabioPedretti]

Any reason this is disabled by default?
If there is a side effect maybe add a note about it in the desc?
Thanks.

[fire332]

It is disabled by default because:

• It'll load the high quality thumbnail as well as whatever thumbnail Youtube loads which is extra data.
• High quality thumbnails makes animations feel stuttery, the degree varies with which TV you have.
• It doesn't replace thumbnails from A/B tests so it'll look jarring having high quality and low quality thumbnails side by side.