v0.2.0: cited GaN and AlN parameter sets

Cited wurtzite valence parameter sets ship with full provenance, verified against closed forms in the test-suite.

• gan_rinke2008(): the consistent GW-based GaN set of Rinke et al., Phys. Rev. B 77, 075202 (2008) (A1..A6, Delta_CR = 10 meV, Delta_SO = 17 meV), as tabulated in Extended Data Table 1 of Chang et al., Nature Electronics 9, 346 (2026). eps_r = 10.4 (E parallel c) from Barker and Ilegems, Phys. Rev. B 7, 743 (1973). The test-suite reproduces the closed-form zone-center splittings (5.20 and 21.80 meV, against accepted experimental values near 5-6 and 22 meV) and the quasi-cubic asymptotic in-plane masses (1.89 and 0.18 m0) from the assembled Hamiltonian.
• aln_rinke2008(): the matching AlN barrier set (Delta_CR = -295 meV from Rinke et al.; Delta_SO = 22 meV from de Carvalho et al., Appl. Phys. Lett. 97, 232101 (2010)). Its permittivity is deliberately NaN and the self-consistent solver refuses to run on it: no vetted value is shipped and none is needed for a barrier.
• One honest comparison is on record in the README: a hard-wall self-consistent run at 4.6e13 cm^-2 puts the gas centroid at 0.62 nm against 0.568 nm for the hard-wall row of the source paper's Table S1, the difference coming from the documented parabolic edge-mass filling. The warning stands: not for publication-grade numbers before the finite-barrier, dispersion-filled v0.3.
• FUNDING.yml added (Patreon sponsor button). 10 tests total.

No API changes; v0.1 code continues to work unchanged.