Move docs editor overlay outside section so fixed positioning works

The editor div was inside #tab-docs (.tab-panel) whose ancestor chain
could trap position:fixed. Moving it to a sibling of <section> so the
full-screen overlay covers the entire viewport unconditionally.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

public/index.html

@@ -141,17 +141,19 @@
         <div id="docs-list"></div>
         <p id="docs-empty" class="hint" hidden>No documents yet — tap + New Document to start writing!</p>
       </div>
-      <div id="docs-editor-view" hidden>
-        <div class="docs-editor-toolbar">
-          <button id="btn-docs-back" class="docs-back-btn">← Back</button>
-          <span id="docs-editor-title" class="docs-editor-title-text"></span>
-          <button id="btn-docs-submit" class="docs-submit-btn">Submit to Parent ✓</button>
-        </div>
-        <div id="docs-editor-frame"></div>
-      </div>
     </div>
   </section>
 
+  <!-- Docs full-screen editor overlay (outside section so fixed positioning is never trapped) -->
+  <div id="docs-editor-view" hidden>
+    <div class="docs-editor-toolbar">
+      <button id="btn-docs-back" class="docs-back-btn">← Back</button>
+      <span id="docs-editor-title" class="docs-editor-title-text"></span>
+      <button id="btn-docs-submit" class="docs-submit-btn">Submit to Parent ✓</button>
+    </div>
+    <div id="docs-editor-frame"></div>
+  </div>
+
   <!-- All-done celebration overlay -->
   <div id="celebration-overlay" hidden>
     <div id="celebration-content">