[Track] Add Rust implementations across the curriculum

Motivation

The README lists Python, TypeScript, Rust, and Julia as the four languages.
A scan of catalog.json shows the actual coverage today:

Language	Lessons	Coverage
Python	427	98.2%
Julia	4	0.9% (Phase 1 only)
TypeScript	2	0.5% (Phase 16 only)
Rust	1	0.2% (Phase 10 L01 bpe.rs)

I'd like to open a long-running track adding Rust implementations to lessons where Rust is a natural fit — pure algorithms, from-scratch math, byte-level work, inference internals. The existing phases/10-llms-from-scratch/01-tokenizers/code/bpe.rs already sets a clean precedent (single file, stdlib-only, lives alongside the Python version), and I'll follow that convention.

Approach

• One PR per lesson — keeps reviews fast (per CONTRIBUTING.md).
• Single .rs file in the lesson's existing code/ directory, no Cargo.toml.
• Mirrors the Python's structure and printed output so readers can diff the two.
• README Lang column updated to Python, Rust in the same PR; node site/build.js run.

First batch (proposed order)

1. Phase 2 L02 linear-regression-from-scratch — pure stdlib math, classic starter
2. Phase 2 L03 logistic-regression-classification
3. Phase 3 L01 the-perceptron
4. Phase 3 L03 backpropagation-from-scratch
5. Phase 7 L02 self-attention-from-scratch

Happy to reorder if there are phases you'd rather see covered first.

Out of scope (for now)

• Lessons that depend on heavy framework parity (PyTorch/JAX internals).
• Lessons whose Python uses regex with lookarounds (e.g. Phase 10 L02) — Rust's regex crate doesn't support these without an external dep. I'll revisit those after the no-deps baseline is established.

First PR coming shortly against Phase 2 L02. Will link it here.

[Ishaq101]

Hi @vincentredrock , I’m currently learning this repo and came across this issue. It seems like a great opportunity for me to contribute while also learning Rust.

May I know if there are any updates from the current contributor working on this issue?