feat: comprehensive WCAG 2.1 AA accessibility audit

- Add aria-labels to menu action buttons (PDF, Print, Contact)
- Add aria-labelledby to toggle checkboxes (desktop + mobile)
- Add -webkit-user-select prefix for Safari compatibility
- Add DynamicCacheControl middleware for HTML pages
- Add accessibility test suite (60-accessibility.test.mjs)
- Add comprehensive accessibility documentation (21-ACCESSIBILITY.md)
- Update Modern Web Techniques doc to mark audit complete

static/css/03-components/_cv-section.css

@@ -43,6 +43,7 @@
 .cv-section summary {
     cursor: pointer;
     list-style: none;
+    -webkit-user-select: none;
     user-select: none;
     position: relative;
 }

static/css/03-components/_sidebar.css

@@ -51,6 +51,7 @@
   summary {
     cursor: pointer;
     list-style: none;
+    -webkit-user-select: none;
     user-select: none;
     position: relative;
     display: flex;

static/css/04-interactive/_toggles.css

@@ -12,6 +12,7 @@
 .toggle-switch {
     display: inline-block;
     cursor: pointer;
+    -webkit-user-select: none;
     user-select: none;
     position: relative;
 }

static/css/04-interactive/_zoom-control.css

@@ -21,6 +21,7 @@
     opacity: 0.7;
     font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', system-ui, sans-serif;
     cursor: move; /* Indicate draggability */
+    -webkit-user-select: none; /* Safari compatibility */
     user-select: none; /* Prevent text selection while dragging */
 }
 

static/css/05-responsive/_breakpoints.css

@@ -479,6 +479,7 @@
         text-transform: uppercase;
         gap: 0.3rem; /* Reduced gap */
         list-style: none;
+        -webkit-user-select: none;
         user-select: none;
         border-bottom: 1px solid #34495e; /* Thinner border */
     }