Extend form handling to support:
- <select> dropdowns: detect options, select by visible text or value
- <textarea> fields: fill with text content
- <input type="file">: upload files by absolute path
- All element types are also discovered inside shadow DOM
Changes:
- find_inputs.js: discover <select> (with options) and <textarea>
- browser.py: import Select, handle new element types in
get_form_inputs() and fill_form_inputs()