Build assets v1

Large build assets that are gitignored in the repo but needed for full-fidelity CI runs.

model.onnx — all-MiniLM-L6-v2 exported to ONNX fp32 (86 MB), produced by scripts/export_minilm_onnx.py and verified against sentence-transformers to 1.19e-07. Kept out of git because it is regenerable and would bloat every clone; hosted here so CI can run the vector arm of the JVM battery instead of silently falling back to keyword-only.