admin: group sources and safe search become rac checkboxes

the assigned sources list is a rac checkboxgroup and safe search uses the same drawn checkbox, extracted to a shared ui component with grouped and standalone modes enforced by a discriminated union. the label carries a 44px pointer-target floor on both axes, the focus ring is driven from rac's focus-visible state and guarded by a test, and toggleSource is gone because the group hands back the whole set.

admin/src/features/configuration/GroupSourcesEditor.tsx

@@ -3,7 +3,8 @@ import { useMutation, useQuery, useQueryClient } from "@tanstack/react-query";
 import * as stylex from "@stylexjs/stylex";
 import { groupSourcesPutMutation, groupSourcesQuery } from "@/lib/queries";
 import type { Blocklist } from "@/lib/types";
-import { sameSet, toggleSource } from "./sourceSet";
+import { sameSet } from "./sourceSet";
+import Checkbox, { CheckboxGroup } from "@/ui/Checkbox";
 import InlineError from "@/lib/InlineError";
 import { styles as shared } from "@/ui/styles";
 import { colors } from "@/ui/tokens.stylex";
@@ -28,13 +29,6 @@ const styles = stylex.create({
 		flexDirection: "column",
 		gap: "0.25rem",
 	},
-	checkboxLabel: {
-		display: "inline-flex",
-		alignItems: "center",
-		gap: "0.5rem",
-		fontSize: "0.875rem",
-		lineHeight: "1.25rem",
-	},
 	buttonRow: {
 		marginTop: "0.75rem",
 		display: "flex",
@@ -66,21 +60,22 @@ export default function GroupSourcesEditor({ groupId, blocklists }: Props) {
 
 	return (
 		<div {...stylex.props(styles.root)}>
-			<ul {...stylex.props(styles.list)}>
-				{blocklists.map((blocklist) => (
-					<li key={blocklist.id}>
-						<label {...stylex.props(styles.checkboxLabel)}>
-							<input
-								type="checkbox"
-								checked={current.includes(blocklist.id)}
-								onChange={() => setSelected(toggleSource(current, blocklist.id))}
-								{...stylex.props(shared.focusRing)}
-							/>
-							{blocklist.name}
-						</label>
-					</li>
-				))}
-			</ul>
+			{/* The section's own "Assigned sources" heading is the visible label; a
+			    Label here would put the same words on screen twice. Ids cross the
+			    React Aria boundary as strings, the same convention as Select. */}
+			<CheckboxGroup
+				aria-label="Assigned sources"
+				value={current.map(String)}
+				onChange={(values) => setSelected(values.map(Number).sort((a, b) => a - b))}
+			>
+				<ul {...stylex.props(styles.list)}>
+					{blocklists.map((blocklist) => (
+						<li key={blocklist.id}>
+							<Checkbox value={String(blocklist.id)}>{blocklist.name}</Checkbox>
+						</li>
+					))}
+				</ul>
+			</CheckboxGroup>
 			<InlineError error={mutation.error} />
 			<div {...stylex.props(styles.buttonRow)}>
 				<button