feat(ingest): downstream on-page-seo technical and schema audit skill

[harshsinghmp]

Classification

actionable-feature

Context & Rationale

AgriciDaniel/on-page-seo provides rigorous technical on-page SEO audits, schema.org JSON-LD structured data validation, semantic tag hierarchy checks, and meta-tag optimization.

Scope & Ingestion Plan

1. Ingest upstream from https://github.com/AgriciDaniel/on-page-seo.
2. Place into skills/marketing/on-page-seo.
3. Register in skills.manifest.json under Growth, Marketing & Social.

Verification Criteria

• skills/marketing/on-page-seo/SKILL.md exists and passes manifest schema validation.
• Registered in skills.manifest.json.
• Validated via bun test.