Switch: the busy status is announced in English, if it is announced at all

[cixzhang]

Who is affected

Anyone using a screen reader who turns on a Switch that does asynchronous
work, and anyone using Astryx in a language other than English.

What happens

While a Switch is busy it renders

{isBusy && <VisuallyHidden role="status">Loading</VisuallyHidden>}

Two things go wrong with that one line.

1. The status is born with its content. The live region is mounted at the
   same moment its text appears. Assistive technology announces changes to a
   live region, so a region that already contains its text when it is inserted
   is usually silent. The person hears nothing at all: they press the switch,
   the switch does not visibly change yet, and nothing tells them the change is
   in flight.
2. The word is hardcoded English. Every other assistive-technology-facing
   string in core goes through the translator — Button announces
   t('@astryx.button.loading') — but Switch says the literal Loading. A
   French or Japanese user hears an English word in the middle of their own
   interface.

Button already does this correctly: it renders the live region
unconditionally and swaps the translated text in and out.

Expected

A busy Switch announces its busy state, in the user's language, through the
persistent live region the repository already provides (useAnnounce, or the
always-mounted-region shape Button uses), with the string routed through the
i18n key system.

Where

packages/core/src/Switch/Switch.tsx — the isBusy branch of switchElement.
Compare with packages/core/src/Button/Button.tsx.

Notes

Found while inventorying Switch's states for the shared accessibility
spec-test contract. The contract does not encode announcements: what an
assistive technology actually says is a real-AT observation and is out of scope
for a runtime contract, so this is filed as its own defect rather than recorded
as a contract failure.

The repository accessibility checklist covers both halves — the "Announcements"
item ("Never render a live region that is born with content") and the "i18n"
item ("Every AT-facing string … goes through useTranslator()").