fix(focus-rings): remove broken [&_input]:focus selectors and fix error state focus-visible

- Strip malformed [[&_input]:focus:*] class fragments from PersonTypeahead
  wrapper divs in both ConversationFilterBar components — PersonTypeahead
  manages its own focus ring; parent selectors were redundant and broken
- Fix WhoWhenSection error state: focus:ring-red-500 → focus-visible:ring-red-500
  so invalid date field ring no longer fires on mouse click

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

frontend/src/lib/components/document/WhoWhenSection.svelte

@@ -71,7 +71,7 @@ $effect(() => {
 				placeholder={m.form_placeholder_date()}
 				maxlength="10"
 				class="block w-full rounded border border-line p-2 text-sm shadow-sm
-                       {dateInvalid ? 'border-red-400 focus:border-red-500 focus:ring-red-500' : 'focus:outline-none focus-visible:ring-2 focus-visible:ring-focus-ring'}"
+                       {dateInvalid ? 'border-red-400 focus:outline-none focus-visible:ring-2 focus-visible:ring-red-500' : 'focus:outline-none focus-visible:ring-2 focus-visible:ring-focus-ring'}"
 				aria-describedby={dateInvalid ? 'date-error' : undefined}
 			/>
 			<input type="hidden" name="documentDate" value={dateIso} />