v0.1.0: one Hamiltonian, every observable

First release. Build a tight-binding Hamiltonian once, as real-space blocks in an orthogonal or nonorthogonal (LCAO-style) basis, and compute its band structure, density of states, Kubo-Greenwood optical conductivity and Landauer (NEGF) transmission from the same Bloch matrices, so spectral, optical and transport statements about one model can never disagree.

Validated against closed forms in the test suite (23 tests): exact chain and SSH dispersions, the analytic chain density of states, graphene Dirac-point closure and the universal optical sheet conductivity e^2/(4 hbar) as the absolute unit anchor, a hand-derived molecular absorption line, exact gauge invariance of the nonorthogonal Kubo velocity, the closed-form chain surface Green function, unit and multichannel transmission, the closed-form single-impurity transmission, and machine-precision agreement between the recursive Green function sweep and dense direct inversion.

Methodological basis: the engine distilled from the pipeline of "Learning the quantum Hamiltonian of defective monolayer MoS2 reveals collective vacancy brightness decoupled from defect count" (https://github.com/Tanvir-Mahmud-Mahim/mos2-vacancy-optics). Dependencies: NumPy and SciPy.