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/protocol.ts

@@ -442,7 +442,10 @@ const errorsSchema = baseCommandSchema.extend({
 
 const keyboardSchema = baseCommandSchema.extend({
   action: z.literal('keyboard'),
-  keys: z.string().min(1),
+  subaction: z.enum(['type', 'press', 'insertText']).optional(),
+  keys: z.string().min(1).optional(),
+  text: z.string().min(1).optional(),
+  delay: z.number().optional(),
 });
 
 const wheelSchema = baseCommandSchema.extend({
@@ -1058,6 +1061,16 @@ export function parseCommand(input: string): ParseResult {
     };
   }
 
+  if (command.action === 'keyboard') {
+    const sub = command.subaction ?? 'press';
+    if ((sub === 'type' || sub === 'insertText') && !command.text) {
+      return { success: false, error: `keyboard ${sub} requires text`, id };
+    }
+    if (sub === 'press' && !command.keys) {
+      return { success: false, error: 'keyboard press requires keys', id };
+    }
+  }
+
   return { success: true, command };
 }