docs: calibration matrix — ONNX vs GGUF vs highheelbgz × ICC profiles 5 encoding paths × ONNX ground truth × 6 models × 6 roles: ONNX (rten) = f32 ground truth GGUF raw u8 CDF, GGUF γ+φ, GGUF i8 signed, GGUF highheelbgz spiral ICC profile per path. Spearman ρ identifies best encoding per model×role. All tools ready: rten, streaming, gamma_phi, LensProfile, calibrate harness. Estimated: ~2.5 hours for complete matrix. https://claude.ai/code/session_01ChLvBfpJS8dQhHxRD4pYNp#113