[codex] Add cactus CQ packaging workflow

[kar-m]

Summary

Adds the cleaned cactus CQ packaging workflow:

• pack native TQH-GPTQ/CQ artifacts into cactus mmap .weights packages
• emit token embeddings as orthogonal CQ4 during packaging
• add production presets for A4V4L1 and A4V4L2
• document an audio-only quantization recipe using the sanitized fixed AV quantizer

Validation

• python -m py_compile on the changed/new export scripts
• local package validation confirmed CQ4 token embedding headers for Qwen3-VL, LFM-VL, and LFM-350M packages