docs(copilot): add comprehensive AI assistant instructions for OSVM

Add detailed GitHub Copilot instructions document covering:
- OSVM CLI project architecture and security fundamentals
- OVSM domain-specific research language syntax and features
- System prompts for AI model planning and execution
- 207 built-in tools for Solana blockchain analysis
- Extensive examples of OVSM language usage patterns
- Implementation guidelines for Rust-based development

This documentation enables AI assistants to understand the project's
three-layer security architecture, zero-trust networking model, and
OVSM language semantics for generating contextually appropriate code
suggestions and maintaining consistency with the project's Rust-only
implementation requirement.

Author: 0xrinegade