fix(settings): raise the TimezonePicker inner gap to match the form rhythm

The picker row sits between two `space-y-4` (16 px) form rows, so the
old `gap-2` (8 px) between the select and the detect button read as a
tighter rhythm than the rest of the profile form. `gap-3` (12 px) keeps
the detect button visually attached to the select (it is a hugged
action) while no longer breaking the cadence the surrounding rows set.

src/components/settings/timezone-picker.tsx

@@ -88,7 +88,7 @@ export function TimezonePicker({
   return (
     <div className="space-y-2">
       <Label htmlFor={id}>{t("settings.timezone")}</Label>
-      <div className="flex flex-col gap-2 sm:flex-row sm:items-center">
+      <div className="flex flex-col gap-3 sm:flex-row sm:items-center">
         <select
           id={id}
           value={value}