feat(physics): Implement gravitational wave propagation (v8 Section 15)

[cnygaard]

Add comprehensive GW physics implementation including:

Wave Equation (□h_μν = 0):

• WaveEquationSolver for 1D and spherical 3D wave propagation
• Finite difference scheme with CFL stability condition

Polarization & Gauge:

• Plus (+) and cross (×) polarization tensors
• TT (transverse-traceless) gauge projection
• Polarization orthogonality and normalization

Binary Inspiral Source:

• Quadrupole formula for GW emission
• Chirp mass and orbital frequency evolution
• Phase and amplitude as functions of time to coalescence

Ringdown:

• Quasi-normal mode frequency and damping time
• Exponential decay with oscillation
• Quality factor computation

Fisher Metric Connection (v8 Key Result):

• h_μν = ℓ_P² · δG_μν^Fisher[δΨ]
• Perturbation from quantum state variations

Detector Response:

• Antenna pattern functions F_+, F_×
• Strain response computation
• SNR estimation

Complete Waveforms:

• GravitationalWaveSignal for full IMR (inspiral-merger-ringdown)
• Frequency-domain waveforms via stationary phase

Also includes Berry curvature additions to quantum_geometry.py:

• Quantum Geometric Tensor Q_μν computation
• Berry curvature Ω_μν extraction
• Kähler structure verification
• Complex structure J with J² = -𝟙

Tests: 59 v8 feature tests (139 total), all passing