feat(fermata): add cargo publish/install metadata

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.

README.md

@@ -13,6 +13,22 @@ v0.1 — first releasable slice:
 
 Out of scope for v0.1: Codex, Gemini, MCP server, audit log, filesystem watcher.
 
+## Install
+
+From a published release (after `cargo publish`):
+
+```bash
+cargo install dirigent_fermata
+```
+
+From source (this monorepo):
+
+```bash
+cargo install --path crates/dirigent_fermata --features cli
+```
+
+This installs the `fermata` binary into `~/.cargo/bin/`.
+
 ## Quick start
 
 ```bash