refactor: replace console.log with structured logger calls

Replace raw `console.log`/`console.error` calls across CLI, API
handlers, and module files with structured logger functions (`step`,
`done`, `warn`, `fail`) from the shared logger library.

This improves log consistency, readability, and makes it easier to
control output formatting and log levels from a single place.

src/features/admin/actions/statsActions.js

@@ -38,6 +38,7 @@
 'use server';
 
 import { query } from '@zen/core/database';
+import { fail } from '../../../shared/lib/logger.js';
 
 /**
  * Get total number of users
@@ -50,7 +51,7 @@ async function getTotalUsersCount() {
     );
     return parseInt(result.rows[0].count) || 0;
   } catch (error) {
-    console.error('Error getting users count:', error);
+    fail(`Error getting users count: ${error.message}`);
     return 0;
   }
 }
@@ -70,7 +71,7 @@ export async function getDashboardStats() {
       }
     };
   } catch (error) {
-    console.error('Error getting dashboard stats:', error);
+    fail(`Error getting dashboard stats: ${error.message}`);
     return { 
       success: false, 
       error: error.message || 'Failed to get dashboard statistics'