docs: implementation plan for publishable harmont-cli crate

Five-task plan landed in a6c632f, b9ec7d1, a3cd1ae, 2dfeff5: two-mode
build.rs (bundled-wasm fast path + dev cross-compile fallback),
include = [...] carrying embedded/*.wasm into the published tarball,
gitignore for the CI-staged wasms, release.yml step pre-building the
four plugin wasms before `cargo publish -p harmont-cli`.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: markovejnovic