Enhance ledger operations and referral lifecycle

Add traceable ledger filtering and permanent referral codes so operators can investigate credit activity without weakening immutable accounting guarantees.

admin-web/src/api/client.ts

@@ -160,6 +160,11 @@ function cursorQuery<T extends CursorQuery>(value?: string | T): CursorQuery | T
 
 type CursorQuery = { cursor?: string };
 
+function ledgerQuery(value?: string | LedgerQuery): CursorQuery | LedgerQuery {
+  if (typeof value === "string") return { cursor: value };
+  return value ? { ...value, referenceId: value.referenceId?.trim() } : {};
+}
+
 export const adminApi = {
   session: () => request<SessionResponse>("/auth/session"),
 
@@ -195,12 +200,12 @@ export const adminApi = {
 
   latestLedger: (value?: string | LedgerQuery) =>
     request<PageResult<LedgerEntry>>(
-      `/credits/ledger${encodeQuery(cursorQuery(value))}`,
+      `/credits/ledger${encodeQuery(ledgerQuery(value))}`,
     ),
 
   ledger: (userId: string, value?: string | LedgerQuery) =>
     request<PageResult<LedgerEntry>>(
-      `/users/${encodeURIComponent(userId)}/ledger${encodeQuery(cursorQuery(value))}`,
+      `/users/${encodeURIComponent(userId)}/ledger${encodeQuery(ledgerQuery(value))}`,
     ),
 
   grantCredits: (payload: CreditGrantRequest) =>