Add uncontested-niche-finder skill

[norightsforlis]

Summary

Adds the uncontested-niche-finder skill: Finds low-competition niche products in deep sub-categories that have no platinum sellers.

Lives in skills/uncontested-niche-finder/SKILL.md and is registered in the README skills table. Public behavior and user-visible workflow only — no internal service names, schema, or implementation details.

Public-Safety Checklist

• No credentials, tokens, keys, or secrets.
• No internal filesystem paths.
• No private Slack, Jira, Notion, admin, or service URLs.
• No private service names or implementation details.
• No customer data or private product data.
• Skill directory name matches SKILL.md frontmatter name.

🤖 Generated with Claude Code

[profunctor]

KISS review: the core promise says this finds niches with no platinum sellers, but Step 2 only drops platinum-owned listings and keeps the remaining non-platinum rows.

In any mixed deep category, the report would call the niche “uncontested” while platinum sellers are still present, which is misleading for sellers. Please either filter out any product/deep category where a platinum seller appears, or weaken the promise/output to “non-platinum listings.”

Also remove the growing-leaf-category handoff unless that skill is published in this catalog.

[profunctor]

Review — uncontested-niche-finder

Summary: Given one Mercado Livre (Brasil) category, walks the category tree for sub-categories deeper than the third level, lists active listings there, drops any held by a platinum seller, and ranks the remaining "uncontested" listings by estimated weekly revenue — surfacing low-competition niches. Markdown niche table with a seller-count signal, cards, optional bar chart, and the standard disclaimer. Read-only.

Findings:

• major — Broken cross-reference to a non-existent "growing-leaf-category skill" (in both description and body). Drop it or ship that skill.
• minor — Copied visualization boilerplate contradicts the skill's own logic: it tells the agent to apply a medal palette including "platina = purple" and render a "Variação"/"Era | Agora" change column with a 🟢/🔴/🆕 legend — but this skill explicitly excludes platinum sellers and has no change/diff columns. Remove the leftover change-column and legend instructions.
• minor — Introduces a richer "Visualization" section (cards, medal palette) with no precedent in the existing three skills; worth a maintainer nod that this is the intended direction.
• nit — README row omits the "weekly" qualifier and disclaimer wording that longer existing rows include.

Frontmatter shape, directory name == name, README table format, EN+pt-BR triggers, read-only, and public-safety all hold. No bugs in query logic. Only finding #1 is worth fixing before merge.