Create performance-marketing.md for AI agent

[pankajthakur1907]

New Agent: Performance Marketing

This PR adds a new performance-marketing.md AI agent to the agents/ directory.

What it does

• Full-funnel Performance Marketing audit across Google, Meta, TikTok, LinkedIn, and Amazon Ads
• • 35+ checks across 6 categories: Attribution & Tracking, ROAS/CPA Efficiency, Budget Allocation, Funnel Performance, Creative & Audience, Cross-Channel Synergy
• • Weighted scoring system (0-100) with grade A-F
• • Critical checks with 5.0x severity multiplier (attribution broken, ROAS below break-even, etc.)
• • Key metrics: Blended ROAS, MER, nCAC, LTV:CAC, Budget Waste %
• • Outputs a detailed performance-marketing-results.md with 30-day action plan

Type of Change

• New sub-skill or feature

Checklist

• Agent follows existing format (name, description, model, maxTurns, tools)
• - [x] All checks have unique IDs (PM-AT1 to PM-CC5)
• - [x] Scoring system aligned with existing scoring-system.md
• - [x] Output format consistent with other audit agents

[pankajthakur1907]

k