Fix docs header theme toggle and command search

[djalmaaraujo]

Summary

• restore Tailwind scanning for local gem component classes used by the docs app
• prevent the command dialog wrapper from requiring an input target before the dialog is opened
• read the header version badge from RubyUI::VERSION

Tests

• pnpm build
• pnpm build:css
• node --check docs/app/javascript/controllers/ruby_ui/command_controller.js
• node --check gem/lib/ruby_ui/command/command_controller.js
• ruby -c docs/app/components/shared/logo.rb
• git diff --check origin/main..HEAD

Note: Rails tests were not run locally because this shell resolves Ruby 2.6, while docs/.ruby-version requires 3.4.7.