feat: implement user authentication and license management system

- Added schema for users, licenses, and license hostnames in the database.
- Created storage utility for reading and writing JSON files.
- Developed user service for user registration, authentication, and retrieval.
- Implemented authentication middleware to protect routes.
- Built LicenseCard component to display license details.
- Created SiteNav component for navigation with user authentication status.
- Established AuthContext for managing authentication state and actions.
- Developed Home page to display available plugins.
- Created LicenseManager page for managing licenses with forms for creation and verification.
- Implemented PluginDetail page to show detailed information about a specific plugin.
- Added utility functions for date formatting.

server/lib/userService.js

@@ -0,0 +1,69 @@
+import bcrypt from "bcryptjs";
+import jwt from "jsonwebtoken";
+import db from "./db.js";
+import { JWT_SECRET, JWT_EXPIRES_IN } from "./config.js";
+
+function serializeUser(row) {
+    if (!row) return null;
+    return {
+        id: row.id,
+        username: row.username,
+        name: row.name,
+        email: row.email,
+        createdAt: row.created_at ? new Date(row.created_at).toISOString() : null
+    };
+}
+
+function signToken(userId) {
+    return jwt.sign({ sub: userId }, JWT_SECRET, { expiresIn: JWT_EXPIRES_IN });
+}
+
+export async function registerUser({ username, name, email, password }) {
+    const passwordHash = await bcrypt.hash(password, 10);
+    try {
+        const [result] = await db.query(
+            `INSERT INTO users (username, name, email, password_hash) VALUES (?, ?, ?, ?)`,
+            [username, name, email, passwordHash]
+        );
+        const user = await getUserById(result.insertId);
+        const token = signToken(user.id);
+        return { user, token };
+    } catch (error) {
+        if (error?.code === "ER_DUP_ENTRY") {
+            const message = error.sqlMessage || "Duplicate";
+            if (message.includes("username")) {
+                error.meta = "USERNAME";
+            } else if (message.includes("email")) {
+                error.meta = "EMAIL";
+            }
+        }
+        throw error;
+    }
+}
+
+export async function authenticateUser(identifier, password) {
+    const [rows] = await db.query(
+        `SELECT * FROM users WHERE username = ? OR email = ? LIMIT 1`,
+        [identifier, identifier]
+    );
+    if (rows.length === 0) {
+        const err = new Error("Onjuiste inloggegevens.");
+        err.meta = "INVALID_CREDENTIALS";
+        throw err;
+    }
+    const row = rows[0];
+    const ok = await bcrypt.compare(password, row.password_hash);
+    if (!ok) {
+        const err = new Error("Onjuiste inloggegevens.");
+        err.meta = "INVALID_CREDENTIALS";
+        throw err;
+    }
+    const user = serializeUser(row);
+    const token = signToken(user.id);
+    return { user, token };
+}
+
+export async function getUserById(id) {
+    const [rows] = await db.query(`SELECT id, username, name, email, created_at FROM users WHERE id = ? LIMIT 1`, [id]);
+    return serializeUser(rows[0]);
+}