✂ Ch.4 — Golden Cut (The Platonic Rupture) [Lane B] · refs #30

# Ch.4 — Golden Cut

**Part**: I | **Lane**: B | **Refs**: #30 · #63

## Rule of Three
1. Core — extreme & mean ratio, algebraic cut
2. Sacred — Euclid II.11 compass construction
3. Philosophy — Plato's Republic line, Kepler's jewel
4. Empirical — quadratic irrational uniqueness
5. Image — golden rectangle

## Acceptance
- [ ] ≥8 pages | `Closes #68`