Book Release Note v0.1.0 — 2026-08-16

The first working book: adds, trades, cancels, and snapshots over a replayed feed.

• Order storage on nlib. nlib::hive owns the resting orders and keeps their addresses stable, one intrusive list per side gives price-time order, and nlib::map indexes by order id, so a trade or cancel is an O(1) lookup and an O(1) unlink.
• nlib::order is the node. The wrapper struct is gone: order carries the list hooks itself, which removed a per-order allocation and an indirection from every traversal.
• Interface and implementation split. Orderbook.h now declares; the bodies moved to src/Orderbook.cpp. The header reads as the contract instead of the mechanism.
• The submodule moved to include/nlib, so the include path is a single directory. Existing clones need git submodule sync && git submodule update --init once after pulling.