feat: redesign website templates with full pages

- Redesigned base.html: dark Minecraft theme, sticky header, responsive grid, cards, server cards with status indicators, profile styles
- index.html: hero section, server list grid, how-to-start steps, features section
- login.html: centered card layout, client-side validation, fetch API
- registration.html: password confirmation, pattern validation, error alerts
- profile.html: new page — skin/cape upload & delete, launcher download links, auth-gated via localStorage token
- templates.go: added /profile route, extended pageData with Username/UUID

internal/templates/html/login.html

@@ -1,42 +1,61 @@
 {{define "content"}}
-<div class="card">
-    <h1>Вход</h1>
-    <form id="loginForm">
-        <label for="username">Логин или Email</label>
-        <input type="text" id="username" name="username" required autocomplete="username">
+<div class="container-narrow">
+    <div class="card text-center">
+        <h1 style="margin-bottom:0.5rem">👋 С возвращением</h1>
+        <p class="muted mb-0">Войди в аккаунт, чтобы управлять профилем и скачать лаунчер.</p>
+    </div>
 
-        <label for="password">Пароль</label>
-        <input type="password" id="password" name="password" required autocomplete="current-password">
+    <div class="card">
+        <div id="alert" class="alert alert-error"></div>
+        <form id="loginForm" novalidate>
+            <label for="username">Логин или Email</label>
+            <input type="text" id="username" name="username" required autocomplete="username" placeholder="player или player@email.com">
 
-        <button type="submit" class="btn">Войти</button>
-    </form>
-    <p id="error" style="color: var(--error); margin-top: 0.75rem; display: none;"></p>
-    <p style="margin-top: 1rem;">Нет аккаунта? <a href="/register">Зарегистрироваться</a></p>
+            <label for="password">Пароль</label>
+            <input type="password" id="password" name="password" required autocomplete="current-password" placeholder="••••••••">
+
+            <button type="submit" class="btn" style="width:100%">Войти</button>
+        </form>
+        <p class="text-center mt-2 muted">Нет аккаунта? <a href="/register">Зарегистрироваться</a></p>
+    </div>
 </div>
 
 <script>
-document.getElementById('loginForm').addEventListener('submit', async (e) => {
+document.getElementById('loginForm').addEventListener('submit', async function(e) {
     e.preventDefault();
-    const form = new FormData(e.target);
-    const res = await fetch('/api/web/login', {
-        method: 'POST',
-        headers: {'Content-Type': 'application/json'},
-        body: JSON.stringify({
-            username: form.get('username'),
-            password: form.get('password')
-        })
-    });
-    const data = await res.json();
-    if (!res.ok) {
-        document.getElementById('error').textContent = data.error || 'Ошибка входа';
-        document.getElementById('error').style.display = 'block';
+    const alert = document.getElementById('alert');
+    alert.className = 'alert alert-error';
+    alert.classList.remove('show');
+
+    const username = document.getElementById('username').value.trim();
+    const password = document.getElementById('password').value;
+
+    if (!username || !password) {
+        alert.textContent = 'Заполните все поля';
+        alert.classList.add('show');
         return;
     }
-    // Save token to localStorage and redirect.
-    localStorage.setItem('token', data.token);
-    localStorage.setItem('uuid', data.uuid);
-    localStorage.setItem('username', data.username);
-    window.location.href = '/';
+
+    try {
+        const res = await fetch('/api/web/login', {
+            method: 'POST',
+            headers: {'Content-Type': 'application/json'},
+            body: JSON.stringify({username, password})
+        });
+        const data = await res.json();
+        if (!res.ok) {
+            alert.textContent = data.error || 'Ошибка входа';
+            alert.classList.add('show');
+            return;
+        }
+        localStorage.setItem('token', data.token);
+        localStorage.setItem('uuid', data.uuid);
+        localStorage.setItem('username', data.username);
+        window.location.href = '/profile';
+    } catch (err) {
+        alert.textContent = 'Ошибка сети. Попробуй ещё раз.';
+        alert.classList.add('show');
+    }
 });
 </script>
 {{end}}