Adds license (MIT OR Apache-2.0), repository (placeholder TODO URL),
readme, keywords, categories, rust-version, dual LICENSE files, and a
README install section. Adds a regression test asserting these fields
remain present so future edits cannot silently break cargo publish.
`cargo install --path crates/dirigent_fermata --features cli` produces
a working `fermata` binary; `cargo publish --dry-run` is clean.
