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/cli/database.js

@@ -18,6 +18,7 @@ process.env.NODE_ENV = process.env.NODE_ENV || 'development';
 
 import { initDatabase, dropAuthTables, testConnection, closePool } from '../core/database/index.js';
 import readline from 'readline';
+import { step, done, warn, fail } from '../shared/lib/logger.js';
 
 async function runCLI() {
   const command = process.argv[2];
@@ -44,25 +45,25 @@ Example:
   try {
     switch (command) {
       case 'init':
-        console.log('🔧 Initializing database...\n');
+        step('Initializing database...');
         const result = await initDatabase();
-        console.log(`\n✅ Success! Created ${result.created.length} tables, skipped ${result.skipped.length} existing tables.`);
+        done(`Created ${result.created.length} tables, skipped ${result.skipped.length} existing tables`);
         break;
 
       case 'test':
-        console.log('🔌 Testing database connection...\n');
+        step('Testing database connection...');
         const isConnected = await testConnection();
         if (isConnected) {
-          console.log('✅ Database connection successful!');
+          done('Database connection successful');
         } else {
-          console.log('❌ Database connection failed!');
+          fail('Database connection failed');
           process.exit(1);
         }
         break;
 
       case 'drop':
-        console.log('⚠️  WARNING: This will delete all authentication tables!\n');
-        console.log('Type "yes" to confirm or Ctrl+C to cancel...');
+        warn('This will delete all authentication tables!');
+        process.stdout.write('  Type "yes" to confirm or Ctrl+C to cancel...\n');
 
         const rl = readline.createInterface({
           input: process.stdin,
@@ -72,9 +73,9 @@ Example:
         rl.question('Confirm (yes/no): ', async (answer) => {
           if (answer.toLowerCase() === 'yes') {
             await dropAuthTables();
-            console.log('✅ Tables dropped successfully.');
+            done('Tables dropped successfully');
           } else {
-            console.log('❌ Operation cancelled.');
+            warn('Operation cancelled');
           }
           rl.close();
           process.exit(0);
@@ -97,8 +98,8 @@ Usage:
         break;
 
       default:
-        console.log(`❌ Unknown command: ${command}`);
-        console.log('Run "npx zen-db help" for usage information.');
+        fail(`Unknown command: ${command}`);
+        process.stdout.write('  Run "npx zen-db help" for usage information.\n');
         process.exit(1);
     }
 
@@ -107,7 +108,7 @@ Usage:
     process.exit(0);
 
   } catch (error) {
-    console.error('❌ Error:', error.message);
+    fail(`Error: ${error.message}`);
     process.exit(1);
   }
 }