* fix(popup): write settings through as they change (v2.8.4)

The popup only saved when you pressed Save, and "Translate this page" sits above
the language selector. So the obvious sequence — open the popup, pick a
different target language, press the big button next to it — translated into the
language you had just moved away from.

Verified in the real popup before the change: firing `change` on the selector
left chrome.storage.sync empty.

Every control now writes through as it changes, and "Translate this page"
persists before it hands off, so the page is translated with what the popup is
showing rather than with what was last saved. Text fields write on `change`
rather than `input`, so a half-typed server URL is not probed and stored on
every keystroke.

The Save button stays, and is still the only thing that says "Saved ✓": a status
line flashing on every dropdown movement is noise, and the dropdown showing the
new value is already the confirmation.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

* docs: restore the backticks the shell ate in the changelog

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

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Co-authored-by: Claude Opus 5 <noreply@anthropic.com>