fix: prevent '?' shortcut from intercepting input in code editors

This adds a guard to the global keydown listener in book.js so that the '?' shortcut does not intercept keypresses when the user is focused inside an input, textarea, or Ace editor block.

Fixes #3064

Author: kartik-py12

crates/mdbook-html/front-end/js/book.js

@@ -654,6 +654,7 @@ aria-label="Show hidden lines"></button>';
         if (window.search && window.search.hasFocus()) {
             return;
         }
+
         const html = document.querySelector('html');
 
         function next() {
@@ -707,6 +708,15 @@ aria-label="Show hidden lines"></button>';
         // Usually needs the Shift key to be pressed
         switch (e.key) {
         case '?':
+            const active = document.activeElement;
+            if (active &&
+                (
+                    active.tagName === 'INPUT' ||
+                    active.tagName === 'TEXTAREA' ||
+                    active.isContentEditable
+                )) {
+                return;
+            }
             e.preventDefault();
             showHelp();
             break;