fix: update audited dependencies

[m-abdelwahab]

Summary

• Fix the failing Cargo audit check by updating rmcp from 0.16 to 1.4
• Update additional audited dependencies flagged by the current RustSec DB:
  • quinn-proto to 0.11.15
  • russh to 0.60.3
  • russh-cryptovec to 0.60.3
• Adjust MCP server metadata construction for rmcp non-exhaustive model structs
• Preserve the previously advertised MCP protocol version, 2025-03-26, so older clients are not forced onto rmcp 1.4's newer 2025-06-18 default

Testing

• cargo fmt --check
• cargo check --locked --all-targets
• cargo test server_info_preserves_advertised_protocol_version --locked
• cargo test --locked
• /private/tmp/cargo-audit-root/bin/cargo-audit audit

Notes

cargo audit now exits successfully. Remaining audit output is limited to allowed warnings.