fix: Accordion starts closed on mobile by default

Removed 'open' attribute from accordion <details> elements to ensure sidebars
start collapsed on mobile view, providing a cleaner initial state.

Changes:
- templates/partials/cv/sidebar.html: Removed open attribute
- templates/cv-content.html: Removed open attributes (2 occurrences)
- templates/language-switch.html: Removed open attributes (2 occurrences)
- tests/mjs/43-mobile-accordion-and-modal-test.mjs: Updated test expectations

Test results:
  ✅ Accordion initially closed
  ✅ Content initially hidden
  ✅ Toggle functionality working perfectly
  ✅ Modal centering maintained (0px offset)

templates/language-switch.html

@@ -32,7 +32,7 @@
     <div class="page-content">
         <!-- Left Sidebar - Skills (first half) -->
         <aside class="cv-sidebar cv-sidebar-left">
-            <details class="sidebar-accordion" open>
+            <details class="sidebar-accordion">
                 <summary class="sidebar-accordion-header">
                     <iconify-icon icon="mdi:brain" width="20" height="20"></iconify-icon>
                     <span>{{if eq .Lang "es"}}Competencias Técnicas{{else}}Technical Skills{{end}}</span>
@@ -86,7 +86,7 @@
 
         <!-- Right Sidebar - Skills (second half) -->
         <aside class="cv-sidebar cv-sidebar-right">
-            <details class="sidebar-accordion" open>
+            <details class="sidebar-accordion">
                 <summary class="sidebar-accordion-header">
                     <iconify-icon icon="mdi:brain" width="20" height="20"></iconify-icon>
                     <span>{{if eq .Lang "es"}}Más Competencias{{else}}More Skills{{end}}</span>