Opravy dle TODO.md - kritické a střední priority

- Opraveny chyby v HTML: špatné URL u CDN, chybějící viewport, úvodní apostrof
- Přidány meta description a keywords na všechny stránky
- Odstraněny nestandardní meta tagy (Kankys Matrix)
- Opraveny všechny externí skripty (HTTPS, crossorigin, integrity)
- Vytvořeny sdílené soubory:
  - web/js/shared.js - společné JS funkce (scrollToTop, setupMobileMenu, setupThemeToggle)
  - web/css/variables.css - CSS proměnné pro témata a design
  - web/css/shared.css - sdílené CSS styly
- Založena struktura pro sdílený kód (js/, css/ adresáře)

Generated by Mistral Vibe.
Co-Authored-By: Mistral Vibe <vibe@mistral.ai>

web/js/shared.js

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+/**
+ * Shared JavaScript functions for NewLukasBlog
+ * Common utilities used across multiple pages
+ */
+
+// ============================================
+// Mobile Menu (Hamburger Menu)
+// ============================================
+function setupMobileMenu() {
+  const menuIcon = document.querySelector(".menu-icon");
+  const menuList = document.querySelector("nav");
+  const hamburgerIcon = document.querySelector(".fa-solid");
+
+  if (menuIcon && hamburgerIcon && menuList) {
+    menuIcon.addEventListener("click", () => {
+      if (hamburgerIcon.classList.contains("fa-bars")) {
+        hamburgerIcon.classList.add("fa-xmark");
+        hamburgerIcon.classList.remove("fa-bars");
+        menuList.style.display = "block";
+      } else {
+        hamburgerIcon.classList.add("fa-bars");
+        hamburgerIcon.classList.remove("fa-xmark");
+        menuList.style.display = "none";
+      }
+    });
+  }
+}
+
+// ============================================
+// Scroll to Top Functionality
+// ============================================
+function scrollToTop() {
+  document.body.scrollTop = 0; // For Safari
+  document.documentElement.scrollTop = 0; // For other browsers
+}
+
+function setupScrollToTopButton(buttonId = "scrollToTopBtn") {
+  const scrollToTopBtn = document.getElementById(buttonId);
+  
+  if (scrollToTopBtn) {
+    window.onscroll = function () {
+      if (document.body.scrollTop > 20 || document.documentElement.scrollTop > 20) {
+        scrollToTopBtn.style.display = "block";
+      } else {
+        scrollToTopBtn.style.display = "none";
+      }
+    };
+  }
+}
+
+// ============================================
+// Theme Toggle Functionality
+// ============================================
+// Base theme toggle - can be extended by specific pages
+function setupThemeToggle(config = {}) {
+  const defaults = {
+    toggleButtonId: "toggleButton",
+    storageKey: "themePreference",
+    defaultTheme: "dark"
+  };
+  
+  const options = { ...defaults, ...config };
+  const toggleButton = document.getElementById(options.toggleButtonId);
+  
+  if (!toggleButton) return;
+
+  // Load saved preference or use default
+  const savedTheme = localStorage.getItem(options.storageKey) || options.defaultTheme;
+  let isDarkMode = savedTheme === "dark";
+
+  // Apply initial theme
+  if (isDarkMode) {
+    document.body.classList.add("dark-theme");
+  } else {
+    document.body.classList.remove("dark-theme");
+  }
+
+  // Toggle function
+  function toggleTheme() {
+    isDarkMode = !isDarkMode;
+    
+    if (isDarkMode) {
+      document.body.classList.add("dark-theme");
+      localStorage.setItem(options.storageKey, "dark");
+    } else {
+      document.body.classList.remove("dark-theme");
+      localStorage.setItem(options.storageKey, "light");
+    }
+    
+    // Call custom callback if provided
+    if (options.onToggle) {
+      options.onToggle(isDarkMode);
+    }
+  }
+
+  // Set up click listener
+  toggleButton.addEventListener("click", toggleTheme);
+}
+
+// ============================================
+// Image Zoom Functionality
+// ============================================
+function setupImageZoom(selector = ".picture", scale = 2.2) {
+  const images = document.querySelectorAll(selector);
+  
+  images.forEach((img, index) => {
+    img.addEventListener("mouseenter", () => {
+      img.style.transform = `scale(${scale})`;
+    });
+
+    img.addEventListener("mouseleave", () => {
+      img.style.transform = "scale(1)";
+    });
+  });
+}
+
+// ============================================
+// Initialize all common functionality
+// ============================================
+document.addEventListener("DOMContentLoaded", function() {
+  setupMobileMenu();
+  setupScrollToTopButton();
+  setupThemeToggle();
+  setupImageZoom();
+});