Fisher-scoring + f32 deep-tail gradient robustness (Opus 4.8)
Half-spectrum hot path, complex64/128 dtype, Fisher-scoring curvature support, and the f32 deep-tail gradient floor (1e-12) fix. Tree-identical to GitHub master. Fast-forward of master.
Half-spectrum hot path, complex64/128 dtype, Fisher-scoring curvature support, and the f32 deep-tail gradient floor (1e-12) fix. Tree-identical to GitHub master. Fast-forward of master.