feat: add auth utilities (Argon2, session tokens)

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

src/lib/server/auth-utils.ts

@@ -0,0 +1,22 @@
+import { hash, verify } from '@node-rs/argon2';
+import crypto from 'crypto';
+
+export async function hashPassword(password: string): Promise<string> {
+	return hash(password);
+}
+
+export async function verifyPassword(hashedPassword: string, password: string): Promise<boolean> {
+	try {
+		return await verify(hashedPassword, password);
+	} catch {
+		return false;
+	}
+}
+
+export function generateSessionToken(): string {
+	return crypto.randomBytes(32).toString('hex');
+}
+
+export function hashSessionToken(token: string): string {
+	return crypto.createHash('sha256').update(token).digest('hex');
+}