Add Cursor plugin support

[shubgaur]

Summary

• Add Cursor plugin marketplace and plugin manifests alongside the existing Claude plugin manifests.
• Document local Cursor plugin/manual skill installation and /frontend-slides usage.
• Add Cursor-specific skill guidance for structured intake, workspace-aware file handling, browser/screenshot verification, accessibility checks, support-file path resolution, and fixture prompts.

Test plan

• Parsed the new Cursor JSON manifests successfully.
• Confirmed the root SKILL.md, packaged skill copy, and local installed Cursor skill stayed in sync.
• Pulled latest upstream changes before opening this PR.

Made with Cursor

[zarazhangrui]

Thanks for adding Cursor plugin support — this is a nice direction.

I did one pass against the current Cursor plugin layout and the repo's existing Claude plugin package. The JSON manifests parse, the root SKILL.md and packaged plugins/frontend-slides/skills/frontend-slides/SKILL.md are in sync, and the package includes the expected skills/ directory.

One small thing before merge: please add the skills pointer to plugins/frontend-slides/.cursor-plugin/plugin.json:

"skills": "./skills/"

Cursor's official plugin examples declare available folders like skills, rules, and agents in the per-plugin manifest, and this repo's Claude plugin manifest already has the same skills pointer. Without it, the plugin may install but not expose /frontend-slides, which is the key behavior this PR is adding.

After that, this looks good to merge from my side.

[rvtawhid420-droid]

"skills": "./skills/"