Add Contracko contract management skills - #1846

Adds Contracko to Business & Marketing, in alphabetical order between "Competitive Ads Extractor" and "Domain Name Brainstormer".

Contracko is an AI contract management platform. contracko/contracko-skills is a public repo of four SKILL.md skills for the job most small companies do badly: keeping track of the contracts they have already signed. The skills cover connecting and organising a workspace, importing contracts, reviewing terms and renewal deadlines, and drafting and filing new agreements.

Against the contribution requirements:

• Real use case. Built for and used by Contracko customers managing vendor, customer and lease agreements. The renewal deadline job is the one that actually costs people money when it is missed.
• Documented. README plus a SKILL.md per skill, with per client setup for Claude.ai, Claude Code, Codex, Cursor and Gemini.
• Accessible. Written for business owners and ops people, not developers.
• Tested. Installs cleanly with npx skills add contracko/contracko-skills, verified in Claude Code and Claude.ai.
• Safe. The underlying MCP server has separate read and write OAuth scopes, so a user can connect read only. Write tools are annotated as destructive where they modify or delete.

The skills pair with Contracko's MCP server, published in the official MCP registry as com.contracko/contracko. A free trial can be started from the sign in screen, so the skills are usable without an existing account.