feat(physics): Implement v8 physics features from theory document

[cnygaard]

Add major physics features from v8 quantum gravity proposal:

Kerr Metric (Section 12):

• compute_kerr_fisher() for rotating black holes
• Frame dragging from quantum correlations g_tφ ∝ ⟨ΔE·ΔL_z⟩
• Horizon radii, ergosphere, and quantum state parameters
• Squeezed thermal coherent state: |Ψ⟩ = D̂(α)Ŝ(ξ)|thermal⟩

Geodesic Equation Solver (Section 13):

• GeodesicSolver with Christoffel symbol computation
• SchwarzschildGeodesics and KerrGeodesics classes
• Circular orbit integration and ISCO calculations
• Principle of least distinguishability: S_Fisher = ∫√(G_μν dx^μ dx^ν) dτ

LQC Quantum Bounce (Section 16.3):

• Modified Friedmann equation: H² = (8πG/3)ρ(1 - ρ/ρ_c)
• Critical density ρ_c = 0.41 ρ_Planck
• LQCPlanckStar model for black hole interior
• Singularity resolution via quantum geometry

Hawking Temperature Quantum Corrections (Section 17.1):

• T = T_H(1 - ℓ_P/(2r_h) + O(ℓ_P²/r_h²))
• Leading and next-to-leading order corrections
• Smooth transition to Planck regime

Tests:

• 26 new tests for all v8 features
• Integration tests for consistency