feat: tools de interaccion estilo Playwright (dropdowns, fill, role, actionable)

4 tools nuevas, wrappers de las primitivas CDP recien creadas:
- dom_find_by_role: localizar por rol ARIA + accessible name (getByRole), devuelve #ref
- dom_wait_actionable: visible+stable+enabled+hit-test antes de click (anti-overlay)
- dom_select_dropdown: desplegables custom (combobox/MUI/select2/headlessui)
- dom_fill: rellenar inputs React/Vue de forma fiable (reemplaza, no concatena)

Total tools: 50 -> 54. uses_functions del app.md actualizado.
Smoke real (Chrome headless 9333) verde para las 4.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

app.md

@@ -63,6 +63,10 @@ uses_functions:
   - cdp_print_pdf_go_browser
   - cdp_select_option_go_browser
   - cdp_set_file_input_go_browser
+  - cdp_wait_actionable_go_browser
+  - cdp_select_dropdown_go_browser
+  - cdp_fill_go_browser
+  - cdp_find_by_role_go_browser
 uses_types: []
 framework: ""
 entry_point: "main.go"