refactor: load RBAC users from API for audit log user filter

Instead of extracting users from log entries, fetch all users
with RBAC roles via dedicated endpoint for complete user list.

src/pages/AdminAuditLog.tsx

@@ -1,4 +1,4 @@
-import { useState, useCallback, useMemo, useEffect } from 'react';
+import { useState, useCallback, useMemo } from 'react';
 import { useNavigate } from 'react-router';
 import { useQuery } from '@tanstack/react-query';
 import { useTranslation } from 'react-i18next';
@@ -415,11 +415,6 @@ function LogEntryCard({ entry, isExpanded, onToggle }: LogEntryCardProps) {
 
 // === Main Page ===
 
-interface KnownUser {
-  name: string;
-  email: string | null;
-}
-
 export default function AdminAuditLog() {
   const { t } = useTranslation();
   const navigate = useNavigate();
@@ -440,9 +435,6 @@ export default function AdminAuditLog() {
   const [exporting, setExporting] = useState(false);
   const [exportError, setExportError] = useState<string | null>(null);
 
-  // Known users accumulated from audit log entries
-  const [knownUsers, setKnownUsers] = useState<Map<number, KnownUser>>(new Map());
-
   // Build query params
   const queryParams = useMemo((): AuditLogFilters => {
     const params: AuditLogFilters = {
@@ -480,23 +472,12 @@ export default function AdminAuditLog() {
     refetchInterval: autoRefresh ? AUTO_REFRESH_INTERVAL : false,
   });
 
-  // Accumulate unique users from audit log entries
-  useEffect(() => {
-    if (!data?.items?.length) return;
-    setKnownUsers((prev) => {
-      const next = new Map(prev);
-      let changed = false;
-      for (const entry of data.items) {
-        const name = entry.user_first_name || entry.user_email || `#${entry.user_id}`;
-        const existing = next.get(entry.user_id);
-        if (!existing || existing.name !== name || existing.email !== entry.user_email) {
-          next.set(entry.user_id, { name, email: entry.user_email });
-          changed = true;
-        }
-      }
-      return changed ? next : prev;
-    });
-  }, [data?.items]);
+  // RBAC users for filter chips
+  const { data: rbacUsers } = useQuery({
+    queryKey: ['rbac-users'],
+    queryFn: () => rbacApi.getRbacUsers(),
+    staleTime: 5 * 60 * 1000,
+  });
 
   const entries = data?.items ?? [];
   const total = data?.total ?? 0;
@@ -669,23 +650,25 @@ export default function AdminAuditLog() {
           <div className="border-t border-dark-700 p-4">
             <div className="grid gap-4 sm:grid-cols-2 lg:grid-cols-3">
               {/* User filter */}
-              {knownUsers.size > 0 && (
+              {rbacUsers && rbacUsers.length > 0 && (
                 <div className="sm:col-span-2 lg:col-span-3">
                   <label className="mb-1 block text-sm font-medium text-dark-300">
                     {t('admin.auditLog.filters.user')}
                   </label>
                   <div className="flex flex-wrap gap-2">
-                    {Array.from(knownUsers.entries()).map(([uid, user]) => {
-                      const isSelected = filters.userId === String(uid);
+                    {rbacUsers.map((ru) => {
+                      const isSelected = filters.userId === String(ru.user_id);
+                      const displayName =
+                        ru.first_name || ru.email || ru.username || `#${ru.user_id}`;
                       return (
                         <button
-                          key={uid}
+                          key={ru.user_id}
                           type="button"
                           aria-pressed={isSelected}
                           onClick={() =>
                             setFilters((prev) => ({
                               ...prev,
-                              userId: isSelected ? '' : String(uid),
+                              userId: isSelected ? '' : String(ru.user_id),
                             }))
                           }
                           className={`flex items-center gap-1.5 rounded-lg border px-3 py-1.5 text-sm transition-colors focus-visible:outline-none focus-visible:ring-2 focus-visible:ring-accent-500 focus-visible:ring-offset-1 focus-visible:ring-offset-dark-900 ${
@@ -703,7 +686,7 @@ export default function AdminAuditLog() {
                           >
                             {isSelected && '✓'}
                           </span>
-                          <span>{user.name}</span>
+                          <span>{displayName}</span>
                         </button>
                       );
                     })}