Proposal: alternative "better" versions of the speed test and stability pages #863

Description

I would like to propose two new pages, index-better.html and stability-better.html: alternative versions of the classic
speed test and of the stability test, with the same features and a different look. They are new files, so the existing
pages (classic, modern, stability) are not touched and nothing changes for anyone who does not open them. The code is in
frontend/better/, with a small change to the Dockerfiles and to entrypoint.sh to ship the two pages.

What they have:

• The same tests as today: the speed test with the server selection and the number of connections, and the stability test
  with the server discovery, the target list (local server, Google, Cloudflare, Apple), the alert threshold, the CSV
  download and the rating
• A round button in the top right corner that opens a panel with every option: light, dark or auto mode, 12 brand colors,
  rounding of buttons and boxes, footer style, font set (system, Inter, Sora, Manrope), text size, high contrast and language
• Three chart styles on the stability page (polished, bands and uPlot, which is only loaded when chosen)
• A test history that stays in the browser, with the link and the image of each result
• Localization in English, Portuguese, Spanish and Swedish, using the same catalog format as Add Swedish interface localization #860 (flat JSON with dotted
  keys, data-i18n, data-i18n-attr, the English text kept in the page as the fallback). The Swedish text is the one from Add Swedish interface localization #860
• A layout that works on small screens, and canvases (meters and chart) that follow the theme, the text size and high contrast

Everything is saved in the browser, and some options can also be set with URL parameters (?theme=, ?brand=, ?lang=,
?font=, ?chart=, ?footer=).

Why it should be implemented

• People who host their own LibreSpeed (home labs, ISPs, companies) often want a page that fits their site: a brand
  color, dark mode, their own language and bigger text for accessibility. Today that means editing the HTML by hand
• The options (text size, high contrast, themes, localization) make the speed test easier to use for people who need them
• It is opt-in and additive. The classic and modern pages stay as they are, so there is no risk of changing what
  people already use, and the new pages can be removed by deleting the files
• The code follows the style of the repository (Prettier, ESLint, Playwright tests) and has no new dependencies, only
  two vendored files that are loaded when needed (the fonts, under SIL OFL, and uPlot, under MIT)

Optional: implementation suggestions

I already have this working on a fork, with 23 new Playwright tests; the whole existing suite (57 tests with Docker)
passes and npm run lint shows no new warnings. It is about 5.8 thousand lines in 46 files, but only about 2 thousand are
code (the rest is CSS, the catalogs, the fonts and uPlot).

Because it is a big change I would like to know first what you prefer before opening a pull request:

1. Do you want this in the repository at all, or would you rather keep it as a separate project?
2. If yes, as one pull request, or split (for example the core pages first, then the theme panel and fonts, then the languages)?
3. How do you want the localization to coexist with Add Swedish interface localization #860? The catalogs of the new pages are in frontend/better/locales,
   so they do not conflict with frontend/locales, and they can be merged later

I also have a few smaller improvements for the classic pages that I can send as separate pull requests if you are
interested: a better privacy dialog, text size and high contrast options, an embedded mode, and a test history.

Optional: screenshots

Updated(2026-10-07)