Correct stale statements on tala.run and rename the vxs storage keys

An audit of the site against the compiler repository found statements
that no longer hold, in all four languages:

- the overview named BUILD.kts as the project definition, while Tazel
  reads one of five names; it now says a project file, BUILD.kts or one
  of four other names;
- the overview and the getting-started guide named Windows and macOS as
  the only development hosts. Ubuntu 26.04 LTS and Fedora 43 are official
  hosts too, and the guide says which toolchain they use;
- the getting-started guide listed the counterparts of the examples in
  C#, C++ and Java; the examples also have Rust ones;
- the project-file page wrote build/debug/Example without the .exe a
  Windows build has.

The talac, Tazel and syntax pages were checked against Documents/CLI.md,
Documents/PROJECT_FILES.md and Spec/Language and are otherwise accurate.
Of the 43 links in the repository, only the address inside the Fira Sans
licence text no longer answers; that text is third-party and verbatim.

The browser storage keys still carried the former name of the language:
vxs-locale-choice, vxs-theme and vxs-forum-theme become tala-locale-choice,
tala-theme and tala-forum-theme. A value under a former key moves to the
current one on the first page load, so no visitor loses a choice; a forum
test covers the move. The npm package is renamed from
@visual-xsharp/website to @progmasoft/tala-website, and the forum assets
get a new version query so Cloudflare serves the new script.

1 files changed, 6 insertions, 2 deletions

diff --git a/Documents/LOCALIZATION.md b/Documents/LOCALIZATION.md
index e139050..f78d09e 100644
--- a/Documents/LOCALIZATION.md
+++ b/Documents/LOCALIZATION.md
@@ -18,7 +18,7 @@ A page has one URL in every language. The language is a preference kept in the b
 
 The rules are pure functions in `frontend/src/locales.ts`:
 
-1. **The visitor's choice.** A language stored under `vxs-locale-choice` in local storage always wins.
+1. **The visitor's choice.** A language stored under `tala-locale-choice` in local storage always wins.
 2. **The browser.** Without a stored choice, the first entry of `navigator.languages` whose primary language is
    published is used. `de-AT` selects German, and `iw`, the former code for Hebrew, selects Hebrew.
 3. **The fallback.** A browser that prefers no published language gets `en-US`.
@@ -44,11 +44,15 @@ A language becomes the stored choice only when a visitor changes it in the menu.
 Earlier versions wrote the language under `vxs-locale` on every visit, which made a real choice indistinguishable
 from the former English default. That key is no longer read.
 
+The keys once carried the former name of the language: `vxs-locale-choice`, `vxs-theme` and `vxs-forum-theme`. A
+value stored under one of them moves to `tala-locale-choice`, `tala-theme` or `tala-forum-theme` the first time a page
+loads, and the former key is removed.
+
 ## The forum page
 
 The forum notice has no language menu. `forum/site.js` shows its one notice in the first browser language that has a
 translation and in English otherwise, and stores nothing about language. It keeps its own theme key,
-`vxs-forum-theme`.
+`tala-forum-theme`.
 
 ## Hebrew and text direction