feat(focus-rings): update interactive widgets to ring-focus-ring

PersonTypeahead, MentionEditor, PanelHistory, UserGroupsSection,
notifications filter buttons, CorrespondentSuggestionsDropdown:
replace ring-accent/ring-primary with ring-focus-ring

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

frontend/src/lib/components/user/UserGroupsSection.svelte

@@ -18,7 +18,7 @@ let selected = $derived([...selectedGroupIds]);
 				name="groupIds"
 				value={group.id}
 				bind:group={selected}
-				class="rounded border-line text-ink focus:ring-accent"
+				class="rounded border-line text-ink focus:ring-focus-ring"
 			/>
 			{group.name}
 		</label>