add auto-signup login and localized auth UI

- backend: userLogin auto-registers missing users and returns auto_registered
- frontend: add responsive auth page (login + signup flow via userLogin) with light/dark mode and logo
- i18n: wire language switching, add translations for cs/en/es/de
- ui/tooling: add Font Awesome integration

backend/scripts/buildTypeScript.php

@@ -4,12 +4,12 @@ require __DIR__ . '/../vendor/autoload.php';
 
 ob_start();
 
-$backend_api = new TPsoft\BugreportBackend\API('typescript', 'import.meta.env.VITE_BACKENDAPI_URL', 'backend');
+$backend_api = new TPsoft\Nutrio\API('typescript', 'import.meta.env.VITE_BACKENDAPI_URL', 'BackendAPI');
 
 $output = ob_get_contents();
 ob_end_clean();
 
-$ts_path = realpath(__DIR__ . '/../../frontend/src').'/backend.js';
+$ts_path = realpath(__DIR__ . '/../../frontend/src').'/BackendAPI.js';
 $suc = file_put_contents($ts_path, $output);
 if ($suc === false) {
 	echo "✗ TypeScript store into file failed\n";

backend/src/API.php

@@ -72,8 +72,21 @@ class API extends APIlite {
 	{
 		$email = $this->normalizeEmail($email);
 		$password = $this->normalizePassword($password);
+		$autoRegistered = false;
 		if (!$this->users()->verifyUser($email, $password)) {
-			throw new \Exception('Invalid email or password');
+			$existing = $this->users()->userBy('email', $email);
+			if (is_array($existing)) {
+				throw new \Exception('Invalid email or password');
+			}
+			$userId = $this->users()->user(null, array(
+				'email' => $email,
+				'password_hash' => $this->users()->hashString($password),
+				'created_at' => '`NOW`'
+			));
+			if ($userId === false) {
+				throw new \Exception('Failed to auto-register user');
+			}
+			$autoRegistered = true;
 		}
 		$user = $this->users()->userBy('email', $email);
 		if (!is_array($user) || !isset($user['user_id'])) {
@@ -87,6 +100,7 @@ class API extends APIlite {
 		}
 		return array(
 			'logged_in' => true,
+			'auto_registered' => $autoRegistered,
 			'user' => $this->mapAuthUser($user)
 		);
 	}