`create-plugin-scaffold` documents unsupported `marketplace.json` metadata fields

Description

The create-plugin-scaffold skill instructs users to add keywords, category and tags as optional metadata on entries in .cursor-plugin/marketplace.json:

6. If repository uses `.cursor-plugin/marketplace.json`, add plugin entry:
   - `name`
   - `source`
   - optional metadata (`description`, `keywords`, `category`, `tags`)

This conflicts with the marketplace schema. A marketplace plugin entry has additionalProperties: false and permits only:

• name
• source
• description
• minClientVersions

The keywords, category and tags fields are supported by .cursor-plugin/plugin.json, not by an individual marketplace.json plugin entry.

Affected files

• create-plugin/skills/create-plugin-scaffold/SKILL.md, lines 50–53
• schemas/marketplace.schema.json, lines 54–79
• schemas/plugin.schema.json, lines 59–71
• scripts/validate-plugins.mjs, lines 34–49

Steps to reproduce

1. Add a plugin entry containing one of the documented fields to .cursor-plugin/marketplace.json:

   {
     "name": "example-plugin",
     "source": "example-plugin",
     "keywords": ["example"]
   }
   

2. Run the repository validator.

3. Validation fails because keywords is an additional property:

   marketplace.json schema validation failed:
     /plugins/0: must NOT have additional properties
   

The same failure occurs with category or tags.

Expected behavior

The scaffold instructions should produce a marketplace entry that conforms to schemas/marketplace.schema.json.

Actual behavior

Following the skill as written can generate an invalid marketplace entry that fails repository validation.

Proposed fix

Update step 6 of create-plugin-scaffold/SKILL.md to state that a marketplace plugin entry accepts:

• Required: name, source
• Optional: description, minClientVersions

Clarify that keywords, category and tags belong in the plugin's .cursor-plugin/plugin.json manifest.

Acceptance criteria

• The skill no longer recommends unsupported properties in a marketplace plugin entry.
• The skill clearly distinguishes marketplace entry metadata from plugin manifest metadata.
• An entry created by following the documented instructions passes scripts/validate-plugins.mjs.

Read create-plugin/skills/create-plugin-scaffold/SKILL.md step 6 alongside schemas/marketplace.schema.json and schemas/plugin.schema.json. Update the documented marketplace fields and clarify the plugin manifest fields, then run scripts/validate-plugins.mjs; done means the instructions describe only schema-supported marketplace properties and validation passes.