Add comprehensive database setup and user management system

- Implement PostgreSQL database schema with users and bookmarks tables
- Add database connection pooling with retry logic and error handling
- Create migration system with automatic schema initialization
- Add database CLI tools for management (init, status, validate, etc.)
- Include comprehensive error handling and diagnostics
- Add development seed data and testing utilities
- Implement health monitoring and connection pool statistics
- Create detailed documentation and troubleshooting guide

Database features:
- Users table with authentication fields and email verification
- Bookmarks table with user association and metadata
- Proper indexes for performance optimization
- Automatic timestamp triggers
- Transaction support with rollback handling
- Connection pooling (20 max connections, 30s idle timeout)
- Graceful shutdown handling

CLI commands available:
- npm run db:init - Initialize database
- npm run db:status - Check database status
- npm run db:validate - Validate schema
- npm run db:test - Run database tests
- npm run db:diagnostics - Full diagnostics

tests/test_folder_logic.js

@@ -0,0 +1,34 @@
+// Test the folder population logic
+const testBookmarks = [
+    { id: 1, title: "Test 1", url: "https://example.com", folder: "Development" },
+    { id: 2, title: "Test 2", url: "https://example2.com", folder: "Development / Tools" },
+    { id: 3, title: "Test 3", url: "https://example3.com", folder: "Personal" },
+    { id: 4, title: "Test 4", url: "https://example4.com", folder: "Development" },
+    { id: 5, title: "Test 5", url: "https://example5.com", folder: "" },
+    { id: 6, title: "Test 6", url: "https://example6.com", folder: "Personal / Finance" }
+];
+
+// Simulate the populateFolderList logic
+function testPopulateFolderList(bookmarks) {
+    // Get unique folder names from existing bookmarks
+    const uniqueFolders = [...new Set(
+        bookmarks
+            .map(bookmark => bookmark.folder)
+            .filter(folder => folder && folder.trim() !== '')
+    )].sort();
+
+    console.log('Test Bookmarks:', bookmarks.length);
+    console.log('Unique Folders Found:', uniqueFolders);
+    console.log('Expected Folders: ["Development", "Development / Tools", "Personal", "Personal / Finance"]');
+    
+    // Verify the logic
+    const expectedFolders = ["Development", "Development / Tools", "Personal", "Personal / Finance"];
+    const isCorrect = JSON.stringify(uniqueFolders) === JSON.stringify(expectedFolders);
+    
+    console.log('Test Result:', isCorrect ? '✅ PASS' : '❌ FAIL');
+    
+    return uniqueFolders;
+}
+
+// Run the test
+testPopulateFolderList(testBookmarks);