ci: pin MSRV 1.79.0 with rust-toolchain.toml (#9)

[OTimileyin]

Summary

Closes #9

Pins the Minimum Supported Rust Version (MSRV) to 1.79.0 by committing a rust-toolchain.toml, updates CI to use that file, and fixes the stale 1.74+ badge in the README.

Changes

rust-toolchain.toml (new)

Pins channel = "1.79.0" with components = ["rustfmt", "clippy"]. This is auto-detected by dtolnay/rust-toolchain in every CI job, ensuring reproducible builds.

.github/workflows/ci.yml

Removed the explicit components: rustfmt from the Quality job's Install Rust step — those components are now declared in rust-toolchain.toml, so the action installs them automatically.

README.md

Updated the Rust badge from Rust-1.74%2B / Rust 1.74+ to Rust-1.79.0 / Rust 1.79.0, matching the pinned toolchain.

Acceptance Criteria

• rust-toolchain.toml exists at repo root with channel = "1.79.0" and ["rustfmt", "clippy"]
• The quality CI job uses that file (auto-detected by dtolnay/rust-toolchain)
• README's Rust 1.74+ claim updated to Rust 1.79.0

Verification

• rust-toolchain.toml passes TOML validation
• .github/workflows/ci.yml passes YAML validation
• Only the three named files were touched

[ameeribro4-sudo]

LGTM