feat: add keyboard command for raw keyboard input (#521)

Adds `keyboard type` and `keyboard insertText` subcommands that
operate on the currently focused element without requiring a selector.

Essential for contenteditable editors (Lexical, ProseMirror, CodeMirror,
Monaco) where `type <selector>` doesn't trigger the editor's internal
event pipeline (beforeinput/DOM mutation).

- `keyboard type <text>` — page.keyboard.type() with real keystrokes
- `keyboard insertText <text>` — page.keyboard.insertText()

Note: `keyboard press` intentionally omitted — the existing top-level
`press` command already operates on current focus.

Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>

src/actions.ts

@@ -1894,8 +1894,21 @@ async function handleKeyboard(
   browser: BrowserManager
 ): Promise<Response> {
   const page = browser.getPage();
-  await page.keyboard.press(command.keys);
-  return successResponse(command.id, { pressed: command.keys });
+  const sub = command.subaction ?? 'press';
+
+  switch (sub) {
+    case 'type':
+      await page.keyboard.type(command.text ?? '', { delay: command.delay });
+      return successResponse(command.id, { typed: true, text: command.text });
+    case 'press':
+      await page.keyboard.press(command.keys ?? '');
+      return successResponse(command.id, { pressed: command.keys });
+    case 'insertText':
+      await page.keyboard.insertText(command.text ?? '');
+      return successResponse(command.id, { inserted: true, text: command.text });
+    default:
+      return errorResponse(command.id, `Unknown keyboard subaction: ${sub}`);
+  }
 }
 
 async function handleWheel(command: WheelCommand, browser: BrowserManager): Promise<Response> {