fix(shortcuts): a shortcut key held with Cmd, Ctrl or Alt runs no shortcut

The application shortcut listener read the key alone, so copying with
Cmd+C or Ctrl+C toggled the CCTV layer and opened the nearest camera,
Cmd+F opened the layers panel and Cmd+1 to 6 changed the visual style.
Chords are now left to the browser. Shift is not a chord, a held key
still repeats, and Escape dismisses search either way.

src/ui/applicationShortcuts.js

@@ -10,7 +10,8 @@ const STYLE_KEYS = Object.freeze({
 /**
  * Bind the application's existing bubbling keyboard shortcuts.
  * Capture-phase surfaces keep first refusal. The caller owns each action and
- * persistence; form controls keep native typing except for Escape.
+ * persistence; form controls keep native typing except for Escape, and a key
+ * held with Cmd, Ctrl or Alt is left to the browser.
  * @param {object} options
  * @param {Document} options.documentRef Keyboard event target.
  * @param {HTMLElement} options.searchInput Additional editing target.
@@ -27,6 +28,13 @@ export function bindApplicationShortcuts({
       event.target?.matches?.('select, input, textarea') ||
       event.target === searchInput;
     if (isFormControl && event.key !== 'Escape') return;
+    // Cmd+C, Ctrl+F, Cmd+1 and the like belong to the browser and the system.
+    // Shift is not a chord here: Shift+C is still C.
+    if (
+      (event.metaKey || event.ctrlKey || event.altKey) &&
+      event.key !== 'Escape'
+    )
+      return;
 
     if (STYLE_KEYS[event.key]) actions.setStyle(STYLE_KEYS[event.key]);
     if (event.key === 'Escape') actions.dismissSearch();

src/ui/visualInput.test.mjs

@@ -117,10 +117,23 @@ test('the supplied search target retains editing even without form markup', () =
   assert.deepEqual(f.calls, [['dismissSearch']]);
 });
 
-test('shortcut extraction does not change repeat or modifier policy', () => {
+test('a held key still repeats its shortcut, and Shift is not a chord', () => {
   const f = shortcuts();
-  f.press('h', new Element(), { repeat: true, ctrlKey: true });
-  assert.deepEqual(f.calls, [['toggleHud']]);
+  f.press('h', new Element(), { repeat: true });
+  f.press('C', new Element(), { shiftKey: true });
+  assert.deepEqual(f.calls, [['toggleHud'], ['toggleCctv']]);
+});
+
+test('browser and system chords on a shortcut key run no shortcut', () => {
+  const f = shortcuts();
+  for (const modifier of ['metaKey', 'ctrlKey', 'altKey'])
+    for (const key of ['1', '6', 'h', 'o', 'v', 'f', 'd', 'c', 'C'])
+      f.press(key, new Element(), { [modifier]: true });
+  // Copying (Cmd+C, Ctrl+C) used to turn CCTV on and open the nearest camera.
+  assert.deepEqual(f.calls, []);
+  f.press('c');
+  f.press('Escape', new Element(), { ctrlKey: true });
+  assert.deepEqual(f.calls, [['toggleCctv'], ['dismissSearch']]);
 });
 
 test('destroy synchronously removes shortcuts and a replacement binds once', () => {