feat(plugins): add Cursor plugin manifest + refresh marketplace branding

[jrusso1020]

What

Two coupled changes to how HyperFrames shows up in agent marketplaces:

1. Adds a Cursor plugin — a new .cursor-plugin/plugin.json at the repo root, alongside the existing .codex-plugin/plugin.json. Both pull from the same skills/ and assets/ at the root, so this repo becomes the single source of truth for the Codex plugin AND the Cursor plugin (same pattern the Codex submission already uses).
2. Refreshes marketplace branding — swaps the 1024×308 "HeyGen HyperFrames" wordmark in assets/logo.png for a 1024×1024 symbol-only icon rasterized from docs/favicon.svg (the Mintlify docs favicon at hyperframes.heygen.com), and renames the marketplace display title from "HyperFrames" to "HyperFrames by HeyGen" in both manifests.

Why

Codex shipped a HyperFrames plugin via openai/plugins#185 and it surfaced two issues once it went live in the marketplace:

• Claude Code / Cursor users have asked for an equivalent — same skills, different marketplace. Since the five skills already live at skills/ at the repo root, the cleanest shape is to register the Cursor plugin in-repo (Cursor's template explicitly supports "single plugin at root") rather than maintain a standalone mirror. Single source of truth: any skill update flows through to both Codex and Cursor consumers via this repo, no mirror to sync.
• The marketplace listing shows a text-only "HeyGen HyperFrames" lockup, which reads as unpolished next to peers like Canva / Remotion / BioRender that all lead with a square brand icon. The branding refresh swaps to the symbol-only mark and makes the "by HeyGen" authorship explicit in the title.

A parallel PR goes out to openai/plugins with the same asset + displayName swap, so both marketplace listings stay visually aligned from the first render.

How

Five files changed, +43 / -4 lines:

1. New .cursor-plugin/plugin.json — mirrors the existing .codex-plugin/plugin.json minus the Codex-specific interface block (displayName/defaultPrompt/capabilities/brandColor/etc. — Cursor's plugin.schema.json rejects those with additionalProperties: false) and with author.url moved to top-level homepage (Cursor's author schema is {name, email} only). Points at the same skills/, assets/logo.png, and LICENSE the Codex side uses.
2. README addendum — one sentence next to the existing Codex install note pointing users at the Cursor Marketplace or the "Load unpacked" sideload path.
3. assets/logo.png — 1024×308 wordmark → 1024×1024 symbol-only icon, transparent background, rasterized from docs/favicon.svg via rsvg-convert.
4. assets/icon.png — 512×512 symbol on solid black → 512×512 symbol with transparent background, same source.
5. Manifest displayName — .codex-plugin/plugin.json's interface.displayName and .cursor-plugin/plugin.json's displayName both bumped from "HyperFrames" to "HyperFrames by HeyGen".

Both PNGs are freshly rasterized from the canonical SVG, so the mark is pixel-perfect at 32 / 64 / 128 / 512 / 1024 and renders cleanly against both light and dark marketplace themes.

Test plan

• .cursor-plugin/plugin.json parses as JSON and validates against plugin.schema.json (name matches the kebab-case regex; author only has {name, email}; skills is a single string pointing at the existing skills/ dir).
• All 5 existing skills/*/SKILL.md files have valid YAML frontmatter with name: and description: (required by Cursor's skill contract — unchanged).
• New assets verified visually at 32 / 128 / 512 px — clean edges, correct green-to-cyan gradient, fully transparent background.
• Clone cursor/plugin-template and run node scripts/validate-template.mjs before submitting to the Cursor Marketplace.
• Load locally in Cursor as an unpacked plugin; verify skill routing + npx hyperframes shell invocation works inside Cursor's sandbox.
• Documentation updated — README addendum added.

Once reviewed + merged, the Cursor submission goes via cursor.com/marketplace/publish (or the kniparko@anysphere.com email path per the template README), and the openai/plugins branding PR lands independently on OpenAI's review track.

— Jerrai