Add AgentStamp — Defensive AI Agent Security Tool

[vinaybhosle]

Adds AgentStamp to the Code section.

AgentStamp is a defensive AI security tool providing trust verification infrastructure for AI agents:

• Identity certification — cryptographic agent identity via ERC-8004 bridge
• Trust scoring — quantitative 0-100 trust scores for agent verification
• Forensic audit trails — tamper-proof behavior logs for post-incident analysis
• x402 micropayments — secure machine-to-machine payment protocol
• MCP server — 14 tools for trust verification, reputation lookup, and stamp management

Complements existing entries like ClawMoat (runtime security) and SkillFortify (supply chain security) by adding an identity and trust verification layer for AI agents.