Add custom buttons to UserInput prompts

[CraigBurden]

Add custom buttons to UserInput prompts

Motivation

Many operator prompts are really a choice: Pass / Fail, Retest / Stop, Accept / Reject. At the moment the only options are an Okay button or a text box, so tests either ask the operator to type a word or chain several yes/no prompts together. This PR lets a prompt offer its own buttons and reports which one was pressed. It works with or without a text box, so a single prompt can ask for a serial number and a verdict.

@htf.plug(prompts=user_input.UserInput)
def inspect_widget(test, prompts):
  test.measurements.widget_looks_ok = prompts.prompt(
      'Does the widget look OK?',
      buttons=[
          user_input.Button('Looks good', color='blue', value='pass'),
          user_input.Button('Damaged', color='red', value='fail'),
      ]).button == 'pass'

# Text and a button together:
response = prompts.prompt('Scan the serial, then choose:', text_input=True,
                          buttons=[user_input.Button('Accept'),
                                   user_input.Button('Reject', color='red')])
response.text, response.button  # ('SN123', 'Reject')

Changes

• user_input.Button(text, color='grey', text_color=None, value=None): color is one of the GUI's built-in blue/red/grey styles or any CSS color. value is the button's response, and defaults to text.
• prompt() / start_prompt() take a keyword-only buttons argument. A prompt with buttons returns PromptResponse(text, button), a NamedTuple. text is '' when text_input is false. Prompts without buttons still return str, so existing callers are unaffected.
• respond(prompt_id, response, button=None): for a button prompt, button must match one of the buttons' responses, otherwise the response is ignored with a warning. Without buttons, behaviour is unchanged.
• Web GUI: htf-user-input-plug shows the buttons in place of Okay/Submit. Clicking a button sends [id, text, button value]. With buttons, Enter in the text box doesn't submit, because a button still has to be chosen. dist/ is rebuilt with npm run build.
• Console: the operator enters any text first, then the buttons are listed by number. They can type the number, the button text or its value, and invalid input re-prompts.
• _asdict() gains a buttons list (text, value, color, text-color), using the same hyphenated key style as text-input and image-url.
• examples/all_the_things.py gets an inspect_widget phase that shows the feature.

Testing

• New cases in test/plugs/user_input_test.py:
  • the buttons entries in _asdict()
  • a blocking button prompt returning PromptResponse
  • text and a button together
  • responses ignored when the button is missing or matches none of the buttons
  • console input resolution
• Full suite passes: pytest test (589 passed).
• Manual GUI check with headless Chrome against a running StationServer:
  • built-in and custom colors render, and Okay is hidden while buttons are shown
  • clicking Fail (value='fail-value') returns PromptResponse('', 'fail-value')
  • text plus buttons: Enter leaves the prompt open, and clicking Reject returns PromptResponse('SN123', 'Reject')
  • a following prompt without buttons still shows Okay and returns ''
• Console checked in a pty: SN9, then maybe (re-prompts), then 2 returns PromptResponse('SN9', 'rej').

🤖 Generated with Claude Code