[PeerX Backlog # 9] Pin MSRV and add a `rust-toolchain.toml` CI check

[ameeribro4-sudo]

Problem Statement
README.md advertises "Rust 1.74+", but no Rust toolchain file is
committed and CI uses whatever dtolnay/rust-toolchain@stable resolves
to. The 36 user-code compile errors being triaged may include MSRV drift.

Why it matters
Reproducible builds require pinned toolchains.

Expected Outcome
A rust-toolchain.toml pins channel = "1.79.0" (or current MSRV).
A CI job asserts the toolchain.

Acceptance Criteria

• rust-toolchain.toml exists at repo root.
• The quality job uses that file.
• README's "Rust 1.74+" claim is updated to match.

Implementation Notes
Use [toolchain] channel = "1.79.0" components = ["rustfmt", "clippy"].

Files Affected

• rust-toolchain.toml (new), README.md, .github/workflows/ci.yml.

Dependencies Issue #6.
Difficulty / Effort 🥉 / XS
Labels ci, dx

[OTimileyin]

Adding rust-toolchain.toml pinning channel = "1.79.0" with rustfmt and clippy, updating the quality CI job to use it, and fixing the README's "Rust 1.74+" claim to match. Strictly the three named files, no unrelated edits. PR up within a day.

[grantfox-oss]

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Next steps:

1. Open a Pull Request referencing this issue (e.g., Closes #9)
2. Your PR will be reviewed by the OpenPeerX maintainers

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[grantfox-oss]

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@OTimileyin's PR #111 was approved and merged by @ameeribro4-sudo.

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👏 Great work, @OTimileyin! Keep contributing to OpenPeerX.