feat: complete P1 specification documentation

- SEC-05: Comprehensive probes specification with ICMP/TCP/HTTP semantics, 2/2 flap damping, and concurrency model
- SEC-07: Complete YAML config schema with sample configuration and apply flow documentation
- SEC-09: Frozen OpenAPI v1 contract with all endpoints, schemas, examples, and comprehensive error handling

All core technical specifications now documented for API contract testing and client type generation.

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <[email protected]>

Author: hemanandr