refactor: Add scrollToSection and fix missing functions

- Add scrollToSection() to utils._hs (was missing after cv-functions.js removal)
- Move error toast close handler to inline hyperscript
- Remove initMenuCloseOnClick() - now integrated into scrollToSection()
- Remove initErrorToastClose() - now hyperscript inline handler
- Remove unused initScrollBehaviorJS() fallback (~70 lines dead code)

This fixes the navigation menu scroll functionality and eliminates
more JavaScript in favor of hyperscript.

static/hyperscript/utils._hs

@@ -170,6 +170,24 @@ def setFooterHover(show)
   end
 end
 
+-- ==============================================================================
+-- NAVIGATION SCROLL
+-- ==============================================================================
+-- Smooth scroll to a section by ID
+def scrollToSection(evt, sectionId)
+  if evt then call evt.preventDefault() end
+  set el to document.getElementById(sectionId)
+  if el is not null
+    call el.scrollIntoView({ behavior: 'smooth' })
+    -- Close the menu after navigation
+    set menu to document.querySelector('.navigation-menu')
+    if menu is not null
+      remove .menu-hover from menu
+      remove .menu-open from menu
+    end
+  end
+end
+
 -- ==============================================================================
 -- KEYBOARD SHORTCUTS
 -- ==============================================================================

static/js/main.js

@@ -91,18 +91,7 @@
         });
     }
 
-    /**
+    // Menu close on nav click is now handled by scrollToSection() in utils._hs
-     * Close menu when navigation links are clicked
-     * CSS handles scrolling with scroll-behavior: smooth
-     */
-    function initMenuCloseOnClick() {
-        document.addEventListener('click', (e) => {
-            const navLink = e.target.closest('.submenu-content a[href^="#"]');
-            if (navLink) {
-                document.querySelector('.navigation-menu')?.classList.remove('menu-hover', 'menu-open');
-            }
-        });
-    }
 
     // =============================================================================
     // PREFERENCES & LANGUAGE
@@ -265,16 +254,7 @@
         toast?.classList.remove('show');
     };
 
-    /**
+    // Error toast close handled by hyperscript inline in error-toast.html
-     * Close button handler for error toast
-     */
-    function initErrorToastClose() {
-        document.addEventListener('click', (e) => {
-            if (e.target.closest('.error-close')) {
-                document.getElementById('error-toast')?.classList.remove('show');
-            }
-        });
-    }
 
     // =============================================================================
     // HTMX EVENT HANDLERS
@@ -491,9 +471,7 @@
      */
     document.addEventListener('DOMContentLoaded', function() {
         initMenuSystem();
-        initMenuCloseOnClick();
         initPreferences();
-        initErrorToastClose();
         initHTMXHandlers();
         handleLandscapeAccordions(); // Auto-open sidebar accordions in landscape mode
         // Note: Scroll behavior now handled by hyperscript in index.html body tag
@@ -501,75 +479,6 @@
         // initScrollBehaviorJS() removed - hyperscript handleScroll() is preferred
     });
 
-    /**
-     * JavaScript-based scroll behavior (fallback for hyperscript)
-     * Desktop: Hide header on scroll down, show on scroll up
-     * Mobile (≤900px): Always show header (CSS handles this, but we skip adding class)
-     */
-    function initScrollBehaviorJS() {
-        let lastScrollY = 0;
-        const scrollThreshold = 100;
-        const actionBar = document.querySelector('.action-bar');
-        const navMenu = document.querySelector('.navigation-menu');
-
-        if (!actionBar) return;
-
-        function isMobileViewport() {
-            return window.innerWidth <= 900;
-        }
-
-        function handleScroll() {
-            const currentScrollY = window.scrollY || window.pageYOffset;
-
-            // Skip header hiding logic on mobile - CSS override handles visibility
-            // but we still avoid adding the class for cleaner state
-            if (isMobileViewport()) {
-                // On mobile, always ensure header is visible
-                actionBar.classList.remove('header-hidden');
-                if (navMenu) navMenu.classList.remove('header-hidden');
-                lastScrollY = currentScrollY;
-                return;
-            }
-
-            // At top of page - always show header
-            if (currentScrollY <= scrollThreshold) {
-                actionBar.classList.remove('header-hidden');
-                if (navMenu && navMenu.classList.contains('menu-open')) {
-                    navMenu.classList.remove('header-hidden');
-                }
-            }
-            // Scrolling DOWN past threshold - hide header
-            else if (currentScrollY > lastScrollY && currentScrollY > scrollThreshold) {
-                actionBar.classList.add('header-hidden');
-                if (navMenu && navMenu.classList.contains('menu-open')) {
-                    navMenu.classList.add('header-hidden');
-                }
-            }
-            // Scrolling UP - show header
-            else if (currentScrollY < lastScrollY) {
-                actionBar.classList.remove('header-hidden');
-                if (navMenu && navMenu.classList.contains('menu-open')) {
-                    navMenu.classList.remove('header-hidden');
-                }
-            }
-
-            lastScrollY = currentScrollY;
-        }
-
-        // Use passive listener for better scroll performance
-        window.addEventListener('scroll', handleScroll, { passive: true });
-
-        // Also handle resize (viewport changes)
-        window.addEventListener('resize', function() {
-            if (isMobileViewport()) {
-                actionBar.classList.remove('header-hidden');
-                if (navMenu) navMenu.classList.remove('header-hidden');
-            }
-        });
-
-        console.log('Scroll behavior JS initialized');
-    }
-
     // =============================================================================
     // HYPERSCRIPT-POWERED FEATURES (NO JS NEEDED)
     // =============================================================================

templates/partials/widgets/error-toast.html

@@ -3,6 +3,7 @@
 <div id="error-toast" class="error-toast no-print" role="alert" aria-live="assertive" style="display: none;">
     <span class="error-icon">⚠️</span>
     <span id="error-message"></span>
-    <button aria-label="Close error message" class="error-close">×</button>
+    <button aria-label="Close error message" class="error-close"
+            _="on click remove .show from #error-toast">×</button>
 </div>
 {{end}}