feat(action-popover): use subtle Action trigger and deprecate positio…

[tamas-sage]

Proposed behaviour

Use a subtle Action button with a three-dots icon, keep it outlined while open, deprecate manual positioning props, and rely on automatic flipping with docs/stories showing text and textless render-prop examples.

Current behaviour

Most of this is implemented (subtle Action button, open-state outline, deprecations, and examples), but the trigger icon is still dropdown in the component/stories instead of three dots.

Checklist

• Commits follow our style guide
• Related issues linked in commit messages if required
• Screenshots are included in the PR if useful
• All themes are supported if required
• Unit tests added or updated if required
• Playwright automation tests added or updated if required
• Storybook added or updated if required
• Translations added or updated (including creating or amending translation keys table in storybook) if required
• Typescript d.ts file added or updated if required
• Related docs have been updated if required

QA

• Tested in provided StackBlitz sandbox/Storybook
• Add new Playwright test coverage if required
• Carbon implementation matches Design System/designs
• UI Tests GitHub check reviewed if required

Additional context

Testing instructions

[edleeks87]

We should be using the PopoverMenu to replace the existing menu, you may need to do some mapping/aliasing to get it to work, happy to chat about it on slack if needed