Fix dropdown secondary style text colors

[LCapistrano25]

Summary

• implement the ActionDropDown widget with style-aware colors and menu rendering
• ensure secondary dropdown menus render enabled items with the expected primary text color and placeholders with textSecondary
• expand the dropdown view model to describe items, selection controller, and style customization options

Testing

• not run (flutter tooling not available in container)

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https://chatgpt.com/codex/tasks/task_e_68f0e24f98c88325963d49e7ac92b4e9