fix: stop a slow reply from pinning a word to hiragana

Making a conversion timeout an ordinary exception put it in the same arm as a
hard API failure, where caching the hiragana fallback is deliberate - so one slow
reply recorded the unconverted form and that word rendered as hiragana for the
life of the cache. A timeout says the request was slow, not that the word has no
conversion, so it now returns the fallback without caching it and the next
message asks again.

The retry test builds its own remembering cache: the shared fixture's get()
always returns null, so against it the API is called every time and the test
would have passed even with the timeout cached.

Co-Authored-By: Claude <noreply@anthropic.com>

0 files changed, 0 insertions, 0 deletions