feat: lazy load ninja-keys + HTML Invoker Commands API

- Lazy load ninja-keys only on CMD+K press (0 requests on initial load)
- Use esm.sh bundled module (3 requests vs ~81 previously)
- Add esm.sh to CSP whitelist
- Implement HTML Invoker Commands API for modals:
  - commandfor="modal-id" + command="show-modal" for opening
  - commandfor="modal-id" + command="close" for closing
  - Removes need for onclick handlers on modal buttons
- Refactor index.html into layout partials (head, body-scripts)
- Add comprehensive tests for both features

templates/partials/modals/contact-modal.html

@@ -17,7 +17,7 @@
                if responseDiv set responseDiv.innerHTML to ''
              end">
     <div class="info-modal-content">
-        <button class="info-modal-close" onclick="document.getElementById('contact-modal').close()" aria-label="{{.UI.ContactModal.Close}}">
+        <button class="info-modal-close" commandfor="contact-modal" command="close" aria-label="{{.UI.ContactModal.Close}}">
             <iconify-icon icon="mdi:close" width="24" height="24"></iconify-icon>
         </button>
 

templates/partials/modals/info-modal.html

@@ -3,7 +3,7 @@
 <dialog id="info-modal" class="info-modal no-print"
         _="on click call closeOnBackdrop(me, event)">
     <div class="info-modal-content">
-        <button class="info-modal-close" onclick="document.getElementById('info-modal').close()" aria-label="{{.UI.PdfModal.Close}}">
+        <button class="info-modal-close" commandfor="info-modal" command="close" aria-label="{{.UI.PdfModal.Close}}">
             <iconify-icon icon="mdi:close" width="24" height="24"></iconify-icon>
         </button>
 

templates/partials/modals/pdf-modal.html

@@ -19,7 +19,8 @@
 
         <!-- Close Button -->
         <button class="info-modal-close"
-                onclick="document.getElementById('pdf-modal').close()"
+                commandfor="pdf-modal"
+                command="close"
                 aria-label="{{.UI.PdfModal.Close}}">
             <iconify-icon icon="mdi:close" width="24" height="24"></iconify-icon>
         </button>

templates/partials/modals/shortcuts-modal.html

@@ -3,7 +3,7 @@
 <dialog id="shortcuts-modal" class="info-modal no-print"
         _="on click call closeOnBackdrop(me, event)">
     <div class="info-modal-content">
-        <button class="info-modal-close" onclick="document.getElementById('shortcuts-modal').close()" aria-label="{{.UI.ShortcutsModal.Close}}">
+        <button class="info-modal-close" commandfor="shortcuts-modal" command="close" aria-label="{{.UI.ShortcutsModal.Close}}">
             <iconify-icon icon="mdi:close" width="24" height="24"></iconify-icon>
         </button>