fix: Display user email instead of Auth0 UID in audit logs (refs #10)

- Add userEmail field to AuditLogEntry type in backend and frontend
- Update audit-log repository to LEFT JOIN with user_profiles table
- Update AdminLogsPage to show email with fallback to truncated userId
- Update AdminLogsMobileScreen with same display logic

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

frontend/src/features/admin/mobile/AdminLogsMobileScreen.tsx

@@ -268,11 +268,15 @@ const AdminLogsMobileScreen: React.FC = () => {
 
             {/* Metadata */}
             <div className="flex flex-wrap gap-x-4 gap-y-1 text-xs text-slate-500">
-              {log.userId && (
+              {log.userEmail ? (
+                <span className="truncate max-w-[180px]">
+                  User: {log.userEmail}
+                </span>
+              ) : log.userId ? (
                 <span className="truncate max-w-[150px]">
                   User: {log.userId.substring(0, 16)}...
                 </span>
-              )}
+              ) : null}
               {log.resourceType && log.resourceId && (
                 <span className="truncate max-w-[150px]">
                   {log.resourceType}: {log.resourceId.substring(0, 10)}...

frontend/src/features/admin/types/admin.types.ts

@@ -388,6 +388,7 @@ export interface UnifiedAuditLog {
   category: AuditLogCategory;
   severity: AuditLogSeverity;
   userId: string | null;
+  userEmail: string | null;
   action: string;
   resourceType: string | null;
   resourceId: string | null;