v0.5.0

Added

• EMA (Effective Medium Approximation) module (core/ema.py) with three methods:
  • volume_weighted — simple volume-weighted average of refractive indices
  • maxwell_garnett — Maxwell-Garnett mixing rule for inclusion-in-host geometries
  • bruggeman — Bruggeman symmetric mixing rule with Newton-iteration solver
• coreshell_geometry property on Particle — computes core-shell geometry using volume-based core identification
• solve_mie_coreshell() — Mie solver for coated spheres using PyMieScatt's core-shell API
• ema_method parameter on solve_mie(), solve_optics(), and MIE_CORESHELL dispatcher
• Integration tests for all EMA methods and core-shell solver (test_ema_integration.py)
• legendre_moments_beta field on AerosolOpticsData — stores DISORT-ready normalized Legendre moments (β_l = k_l/(2l+1))
• Updated coated_fractal_aggregate example — compares four Mie approximations with spectral plots

Changed

• Refactored Particle.effective_refractive_index to delegate to EMA module (backward compatible)
• Simplified pipeline example using ParticleOptics.from_aerosol3d()

Fixed

• Removed unsupported deltam flag, reverted to ASCII output for libRadtran 2.0.6 compatibility