task: #3616090 Write the project name as Rightup

Issue: #3616090 Initialize the Rightup site template recipe and start the 1.0.x branch

Writes the project name as Rightup everywhere a person reads it, replacing the mixed-caps form the initial commit used:

• recipe.yml — name: Rightup, which is what the installer's "Choose a site template" card shows.
• README.md — heading and badge label.
• CHANGELOG.md, AGENTS.md, and the testing-user scripts and their README.

Machine names are untouched: the recipe directory, the package name drupal/rightup and the theme's vartheme_bs5_rightup all stay as they are.

AI-Generated: Yes

Checkpoints:

• File an issue
• Addition/Change/Update/Fix
• Testing to ensure no regression
• Automated unit testing coverage
• Automated functional testing coverage
• UX/UI designer responsibilities
• Readability
• Accessibility
• Performance
• Security
• Developer Documentation
• User Guide Documentation
• Reviewed by human
• Code review by maintainers
• Full testing and approval
• Credit contributors
• Review with the product owner
• Release notes snippet
• Release