67246c69e5
- Settings sidebar was a fixed-width vertical list with no responsive
breakpoint, squeezing the form into a sliver on mobile. Turn it into
a horizontal scrollable tab bar under md, vertical sidebar above.
- setLocale() fired the PATCH and swallowed the result with
.catch(() => {}) — never checked res.ok, no success/failure feedback.
A failed save (expired session, network blip) looked identical to a
successful one. Now returns a boolean, reverts local state on
failure, and the settings form toasts success/failure.
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>