NCSX — developer guide

This guide is a stub. Content is coming as the docs settle.

Things this guide will cover:

• Package layout — @emdzej/ncsx-chassis, -cabd, -coder, -function-list, -identity, -INPAX-cabi-provider, …
• The CABI/CDH bridge — how the per-CABD IPOs call back into host state.
• Per-dispatch cabd-par seeding (matching NCSEXPER's FUN_00402c70).
• Encoding / decoding netto bytes ↔ FSW/PSW values.
• Building from source + running the test suite.
• Reverse-engineering notes — see docs/ in the repo for the architecture deep-dives.

In the meantime, docs/STATUS.md captures what's wired and what's pending.