feat(SEO): implement SEO configuration and meta tag management

- Added SEO defaults and route-specific configurations for improved search engine visibility.
- Introduced functions to normalize paths and retrieve SEO settings based on the current route.
- Enhanced server-side rendering to dynamically update meta tags for title, description, and robots directives.
- Created a utility for managing SEO-related meta and link tags in the frontend, ensuring consistent application of SEO practices across routes.
- Updated sitemap with new last modification dates and removed outdated entries for better search engine indexing.

backend/server.js

@@ -69,6 +69,80 @@ function captureRawBody(req, res, buf, encoding) {
 const __filename = fileURLToPath(import.meta.url);
 const __dirname = path.dirname(__filename);
 
+const SEO_DEFAULTS = {
+  title: 'Trainingstagebuch – Vereinsverwaltung für Tischtennis, Trainingsplanung & Turniere',
+  description: 'Trainingstagebuch ist die Software für Tischtennisvereine: Mitgliederverwaltung, Trainingsplanung, Trainingstagebuch, Gruppen, Turniere, Team-Management, Statistiken und MyTischtennis-Integration.',
+  robots: 'index,follow',
+};
+
+const SEO_ROUTE_CONFIG = {
+  '/': {
+    title: SEO_DEFAULTS.title,
+    description: SEO_DEFAULTS.description,
+    robots: 'index,follow',
+  },
+  '/login': {
+    title: 'Login | Trainingstagebuch',
+    description: 'Im Trainingstagebuch einloggen und Vereinsdaten, Trainingsplanung, Mitglieder und Turniere verwalten.',
+    robots: 'noindex,follow',
+  },
+  '/register': {
+    title: 'Registrieren | Trainingstagebuch',
+    description: 'Kostenlos im Trainingstagebuch registrieren und die Vereinsverwaltung für Tischtennisvereine kennenlernen.',
+    robots: 'noindex,follow',
+  },
+  '/activate': {
+    title: 'Konto aktivieren | Trainingstagebuch',
+    description: 'Aktivierung des Benutzerkontos im Trainingstagebuch.',
+    robots: 'noindex,follow',
+  },
+  '/forgot-password': {
+    title: 'Passwort vergessen | Trainingstagebuch',
+    description: 'Zugang zum Trainingstagebuch wiederherstellen.',
+    robots: 'noindex,follow',
+  },
+  '/reset-password': {
+    title: 'Passwort zurücksetzen | Trainingstagebuch',
+    description: 'Passwort im Trainingstagebuch sicher zurücksetzen.',
+    robots: 'noindex,follow',
+  },
+  '/impressum': {
+    title: 'Impressum | Trainingstagebuch',
+    description: 'Impressum von Trainingstagebuch.',
+    robots: 'noindex,follow',
+  },
+  '/datenschutz': {
+    title: 'Datenschutzerklärung | Trainingstagebuch',
+    description: 'Datenschutzerklärung von Trainingstagebuch.',
+    robots: 'noindex,follow',
+  },
+};
+
+function normalizeSeoPath(pathname = '/') {
+  if (!pathname || pathname === '') return '/';
+  if (pathname === '/') return '/';
+  return pathname.endsWith('/') ? pathname.slice(0, -1) : pathname;
+}
+
+function getSeoConfigForPath(pathname = '/') {
+  const normalizedPath = normalizeSeoPath(pathname);
+  const matchedPrefix = Object.keys(SEO_ROUTE_CONFIG)
+    .filter((routePath) => routePath !== '/' && normalizedPath.startsWith(routePath))
+    .sort((a, b) => b.length - a.length)[0];
+
+  return (matchedPrefix && SEO_ROUTE_CONFIG[matchedPrefix])
+    || SEO_ROUTE_CONFIG[normalizedPath]
+    || { ...SEO_DEFAULTS, robots: 'noindex,follow' };
+}
+
+function escapeHtmlAttribute(value = '') {
+  return String(value)
+    .replace(/&/g, '&')
+    .replace(/"/g, '"')
+    .replace(/</g, '&lt;')
+    .replace(/>/g, '&gt;');
+}
+
 // CORS-Konfiguration - Socket.IO hat seine eigene CORS-Konfiguration
 app.use(cors({
   origin: true,
@@ -166,12 +240,53 @@ const setCanonicalTag = (req, res, next) => {
       const protocol = req.protocol || 'https';
       const host = req.get('host') || 'tt-tagebuch.de';
       const canonicalHost = host.replace(/^www\./, ''); // Entferne www falls vorhanden
-      const canonicalUrl = `${protocol}://${canonicalHost}${req.path === '/' ? '' : req.path}`;
+      const normalizedPath = normalizeSeoPath(req.path);
+      const canonicalUrl = `${protocol}://${canonicalHost}${normalizedPath === '/' ? '' : normalizedPath}`;
+      const seo = getSeoConfigForPath(normalizedPath);
 
-      // Ersetze den kanonischen Tag
-      const updatedData = data.replace(
+      let updatedData = data.replace(
+        /<title>[^<]*<\/title>/,
+        `<title>${escapeHtmlAttribute(seo.title)}</title>`
+      );
+
+      updatedData = updatedData.replace(
+        /<meta name="description" content="[^"]*" \/>/,
+        `<meta name="description" content="${escapeHtmlAttribute(seo.description)}" />`
+      );
+
+      updatedData = updatedData.replace(
+        /<meta name="robots" content="[^"]*" \/>/,
+        `<meta name="robots" content="${escapeHtmlAttribute(seo.robots)}" />`
+      );
+
+      updatedData = updatedData.replace(
         /<link rel="canonical" href="[^"]*" \/>/,
-        `<link rel="canonical" href="${canonicalUrl}" />`
+        `<link rel="canonical" href="${escapeHtmlAttribute(canonicalUrl)}" />`
+      );
+
+      updatedData = updatedData.replace(
+        /<meta property="og:title" content="[^"]*" \/>/,
+        `<meta property="og:title" content="${escapeHtmlAttribute(seo.title)}" />`
+      );
+
+      updatedData = updatedData.replace(
+        /<meta property="og:description" content="[^"]*" \/>/,
+        `<meta property="og:description" content="${escapeHtmlAttribute(seo.description)}" />`
+      );
+
+      updatedData = updatedData.replace(
+        /<meta property="og:url" content="[^"]*" \/>/,
+        `<meta property="og:url" content="${escapeHtmlAttribute(canonicalUrl)}" />`
+      );
+
+      updatedData = updatedData.replace(
+        /<meta name="twitter:title" content="[^"]*" \/>/,
+        `<meta name="twitter:title" content="${escapeHtmlAttribute(seo.title)}" />`
+      );
+
+      updatedData = updatedData.replace(
+        /<meta name="twitter:description" content="[^"]*" \/>/,
+        `<meta name="twitter:description" content="${escapeHtmlAttribute(seo.description)}" />`
       );
 
       res.setHeader('Content-Type', 'text/html');