ci: add Rust CI workflow

[inyellowbus]

Add CI workflow for pull requests: audit, fmt, clippy, cargo check, cargo test, network tests.

[Copilot]

Pull request overview

Adds a GitHub Actions CI workflow for Rust pull requests to standardize basic quality gates (security audit, formatting, linting, compilation checks, unit/integration tests, and network tests) for the Rust workspace under src/.

Changes:

• Pin Clippy as a required Rust toolchain component in src/rust-toolchain.toml.
• Add .github/workflows/ci.yml with jobs for cargo-audit, formatting checks, clippy + cargo check, and test runs (including network tests).

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 5 comments.

File	Description
src/rust-toolchain.toml	Ensures Clippy is available for the pinned toolchain.
.github/workflows/ci.yml	Introduces PR CI pipeline covering audit/fmt/check/tests and network tests.

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.

[bvscd]

Run set -euo pipefail
error: unexpected argument '--config' found

rgo audit [OPTIONS] [COMMAND]

For more information, try '--help'.
cargo-audit report: total vulnerabilities, critical.
/home/runner/work/_temp/f6db3237-8a6c-40e6-9c72-c05faa93496b.sh: line 13: [: : integer expression expected
/home/runner/work/_temp/f6db3237-8a6c-40e6-9c72-c05faa93496b.sh: line 20: [: : integer expression expected
No RustSec advisories found.
/home/runner/work/_temp/f6db3237-8a6c-40e6-9c72-c05faa93496b.sh: line 25: [: : integer expression expected
No critical RustSec advisories found.