feat(billing): show user display name in ledger records

Co-authored-by: Cursor <cursoragent@cursor.com>

server/pagination.mjs

@@ -200,7 +200,7 @@ export async function listLedgerPaged(pool, query) {
     params,
   );
   const [rows] = await pool.query(
-    `SELECT l.id, l.user_id, u.username, l.type, l.amount_cents, l.tokens,
+    `SELECT l.id, l.user_id, u.username, u.display_name, l.type, l.amount_cents, l.tokens,
             l.session_id, l.note, l.created_at
      FROM h5_billing_ledger l
      JOIN h5_users u ON u.id = l.user_id
@@ -214,6 +214,7 @@ export async function listLedgerPaged(pool, query) {
       id: Number(row.id),
       userId: row.user_id,
       username: row.username,
+      displayName: row.display_name,
       type: row.type,
       amountCents: Number(row.amount_cents),
       tokens: Number(row.tokens),