Replace all mock data in admin and board pages with real data

- Admin members page now loads real member data from NocoDB API
- Admin users page fetches actual users from Keycloak with tier determination
- Board members page uses real member data with proper transformations
- Admin payments page generates payment records from dues tracking data
- Created new /api/admin/users endpoint for Keycloak user management
- All stats cards now calculate from real data instead of hardcoded values
- Removed all mock/placeholder data arrays from production pages

🤖 Generated with Claude Code

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

server/api/admin/users.get.ts

@@ -0,0 +1,64 @@
+// server/api/admin/users.get.ts
+
+export default defineEventHandler(async (event) => {
+  try {
+    const { createKeycloakAdminClient } = await import('~/server/utils/keycloak-admin');
+    const { determineMemberTierFromKeycloak } = await import('~/server/utils/member-tiers');
+    
+    // Initialize Keycloak admin client
+    const keycloakAdmin = createKeycloakAdminClient();
+    
+    // Get all users from Keycloak
+    const keycloakUsers = await keycloakAdmin.getUsers();
+    
+    // Filter out service accounts and transform the data
+    const users = keycloakUsers
+      .filter((user: any) => !user.username?.startsWith('service-account-'))
+      .map((user: any) => {
+        // Determine tier/role from groups
+        const tierResult = determineMemberTierFromKeycloak(user);
+        
+        return {
+          id: user.id,
+          username: user.username,
+          email: user.email,
+          firstName: user.firstName,
+          lastName: user.lastName,
+          enabled: user.enabled,
+          emailVerified: user.emailVerified,
+          createdTimestamp: user.createdTimestamp,
+          groups: user.groups || [],
+          tier: tierResult.tier,
+          tierSource: tierResult.source,
+          tierConfidence: tierResult.confidence,
+          // Note: Keycloak doesn't track last login by default
+          // This would need to be implemented via events or custom attributes
+          lastLogin: user.attributes?.lastLogin?.[0] || null
+        };
+      });
+    
+    console.log(`[API] Retrieved ${users.length} users from Keycloak`);
+    
+    return {
+      success: true,
+      data: {
+        users,
+        total: users.length,
+        dataSource: 'keycloak'
+      }
+    };
+  } catch (error: any) {
+    console.error('[API] Error fetching users:', error);
+    
+    // Return empty list on error instead of throwing
+    return {
+      success: false,
+      data: {
+        users: [],
+        total: 0,
+        dataSource: 'unavailable',
+        error: error.message
+      }
+    };
+  }
+});