admin: associate inline field errors with their inputs

network assignment rows, activity filters, and the settings password pair now mark the offending input with aria-invalid and point it at the error text with aria-describedby. the prefix validator returns the row and field it is about, and any row mutation clears a message that named a position. settings numeric fields carry aria-invalid on an unparseable value.

admin/src/features/clients/prefixEditor.ts

@@ -55,11 +55,20 @@ export function isDirty(state: PrefixEditorState): boolean {
 	});
 }
 
-export function firstProblem(rows: PrefixRow[]): string | null {
-	for (const [i, row] of rows.entries()) {
-		if (row.prefix.trim() === "") return `Row ${i + 1}: prefix is required.`;
+/** Which input the message is about, so the editor can point that input at it. */
+export interface PrefixProblem {
+	index: number;
+	field: "prefix" | "priority";
+	message: string;
+}
+
+export function firstProblem(rows: PrefixRow[]): PrefixProblem | null {
+	for (const [index, row] of rows.entries()) {
+		if (row.prefix.trim() === "")
+			return { index, field: "prefix", message: `Row ${index + 1}: prefix is required.` };
 		const priority = row.priority.trim();
-		if (priority !== "" && !/^\d+$/.test(priority)) return `Row ${i + 1}: priority must be a whole number.`;
+		if (priority !== "" && !/^\d+$/.test(priority))
+			return { index, field: "priority", message: `Row ${index + 1}: priority must be a whole number.` };
 	}
 	return null;
 }