feat: Refactor user management to replace email with username across the application

src/lib/init-db.js

@@ -273,7 +273,7 @@ export default function initializeDatabase() {
 		CREATE TABLE IF NOT EXISTS users (
 			id TEXT PRIMARY KEY DEFAULT (lower(hex(randomblob(16)))),
 			name TEXT NOT NULL,
-			email TEXT UNIQUE NOT NULL,
+			username TEXT UNIQUE NOT NULL,
 			password_hash TEXT NOT NULL,
 			role TEXT CHECK(role IN ('admin', 'project_manager', 'user', 'read_only')) DEFAULT 'user',
 			created_at TEXT DEFAULT CURRENT_TIMESTAMP,
@@ -309,9 +309,36 @@ export default function initializeDatabase() {
 		);
 
 		-- Create indexes for performance
-		CREATE INDEX IF NOT EXISTS idx_users_email ON users(email);
+		CREATE INDEX IF NOT EXISTS idx_users_username ON users(username);
 		CREATE INDEX IF NOT EXISTS idx_sessions_token ON sessions(session_token);
 		CREATE INDEX IF NOT EXISTS idx_sessions_user ON sessions(user_id);
 		CREATE INDEX IF NOT EXISTS idx_audit_user_timestamp ON audit_logs(user_id, timestamp);
 	`);
+
+	// Migration: Add username column and migrate from email if needed
+	try {
+		// Check if username column exists
+		const columns = db.prepare("PRAGMA table_info(users)").all();
+		const hasUsername = columns.some(col => col.name === 'username');
+		const hasEmail = columns.some(col => col.name === 'email');
+
+		if (!hasUsername && hasEmail) {
+			// Add username column
+			db.exec(`ALTER TABLE users ADD COLUMN username TEXT;`);
+			
+			// Migrate existing email data to username (for development/testing)
+			// In production, you might want to handle this differently
+			db.exec(`UPDATE users SET username = email WHERE username IS NULL;`);
+			
+			// Create unique index on username
+			db.exec(`CREATE UNIQUE INDEX IF NOT EXISTS idx_users_username_unique ON users(username);`);
+			
+			console.log("✅ Migrated users table from email to username");
+		} else if (!hasUsername) {
+			// If neither username nor email exists, something is wrong
+			console.warn("⚠️  Users table missing both username and email columns");
+		}
+	} catch (e) {
+		console.warn("Migration warning:", e.message);
+	}
 }