Enhance SEO and feedback features across the application

- Updated index.html with improved meta tags for SEO, including author and theme color.
- Added a feedback dialog in ImprintContainer.vue for user feedback submission.
- Refactored LoginForm.vue to utilize a utility for cookie management, simplifying profile persistence.
- Introduced new routes and schemas for feedback in the router and server, enhancing SEO and user experience.
- Improved ChatView.vue with better error handling and command table display.
- Implemented feedback API endpoints in server routes for managing user feedback submissions and admin access.

These changes collectively improve the application's SEO, user interaction, and feedback management capabilities.

client/src/utils/profileCookie.js

@@ -0,0 +1,39 @@
+const PROFILE_COOKIE_NAME = 'singlechat_profile';
+const PROFILE_COOKIE_MAX_AGE = 60 * 60 * 24 * 365;
+
+function readCookie(name) {
+  const prefix = `${name}=`;
+  const cookie = document.cookie
+    .split('; ')
+    .find((entry) => entry.startsWith(prefix));
+
+  return cookie ? cookie.slice(prefix.length) : null;
+}
+
+export function readProfileCookie() {
+  const cookieValue = readCookie(PROFILE_COOKIE_NAME);
+  if (!cookieValue) return null;
+
+  try {
+    return JSON.parse(decodeURIComponent(cookieValue));
+  } catch (error) {
+    console.warn('Profil-Cookie konnte nicht gelesen werden:', error);
+    return null;
+  }
+}
+
+export function writeProfileCookie(profile) {
+  const normalizedProfile = {
+    nickname: typeof profile.nickname === 'string' ? profile.nickname.trim() : '',
+    gender: typeof profile.gender === 'string' ? profile.gender : '',
+    age: Number(profile.age) || 18,
+    country: typeof profile.country === 'string' ? profile.country : ''
+  };
+
+  document.cookie = [
+    `${PROFILE_COOKIE_NAME}=${encodeURIComponent(JSON.stringify(normalizedProfile))}`,
+    `Max-Age=${PROFILE_COOKIE_MAX_AGE}`,
+    'Path=/',
+    'SameSite=Lax'
+  ].join('; ');
+}