doc: expand API reference + JS/TS integration walkthrough toward v1.0

[kalwalt]

Summary

Expand documentation ahead of a stable release: complete module-level API docs on the public surface, plus an integration walkthrough for JS/TS (WASM) consumers.

Scope

• Rustdoc: ensure every public item in webarkitlib-rs (esp. kpm, kpm::freak::visual_database, ar2, backend traits) has module- and item-level docs with examples.
• WASM/JS integration guide: end-to-end walkthrough using @webarkit/webarkitlib-wasm (WasmKpmHandle detect flow), mirroring the browser NFT demo.
• Usage examples: native (simple_nft) + browser, cross-linked from README.

Notes

• Best done after the clippy refactor: reduce too-many-arguments warnings (clippy::too_many_arguments) #83 + coverage test(core): cover error/validation branches in ar/pattern.rs + kpm/freak/pyramid.rs (5 lines) #224 cleanup so the API surface is stable.
• Consider #![warn(missing_docs)] on the public crate once coverage is sufficient.