improvement: enrich plugin.json and marketplace.json metadata

[Luis85]

Context

Part of the plugin audit in #444 (§2, §5, R7 + Quick Wins). The generated plugin.json is missing fields that enable IDE validation and improve marketplace discoverability. The marketplace.json plugin entry is missing a category field required for official marketplace display.

Changes to plugin.json generation (scripts/build-claude-plugin.ts)

{
  "$schema": "https://json.schemastore.org/claude-code-plugin-manifest.json",
  "homepage": "https://luis85.github.io/agentic-workflow",
  "keywords": ["specorator", "spec-driven", "agentic", "workflow", "claude-code"],
  ...existing fields...
}

Changes to marketplace.json

Add "category": "development" to the Specorator plugin entry.

Valid category values: development, productivity, security, database, deployment, design, monitoring, location, learning.

Optional: userConfig

Evaluate whether to expose default_spec_depth (or similar) as a user-configurable setting in plugin.json. Note: sensitive: true fields share a hard ~2 KB keychain limit with OAuth tokens.

Definition of Done

• plugin.json generation includes $schema, homepage, keywords
• marketplace.json has category: "development" in the plugin entry
• check:claude-plugin validates $schema and category presence (or tracked in validator issue)
• Verify gate green

References

• Parent audit: research: Claude plugin developer best-practices audit — gaps, standards, refactor opportunities #444 §2, §5, R7, Quick Wins
• SchemaStore: https://json.schemastore.org/claude-code-plugin-manifest.json
• Marketplace spec: https://code.claude.com/docs/en/plugin-marketplaces