Single-source the version from package.json (closes #5)

src/index.ts imports package.json for VERSION and bin/quak.ts passes
VERSION to commander, so package.json is the only place the version is
written. tsc copies package.json to dist/package.json, so the import
resolves from the built output; script/build runs the built CLI with
--version to prove it. A test checks VERSION and quak --version against
package.json.

Model: opus-5-5

src/index.ts

@@ -1,4 +1,8 @@
-export const VERSION = "0.0.0";
+// package.json is the one place the version is written. tsc copies it to
+// dist/package.json, so this path resolves from source and from dist/src/.
+import pkg from "../package.json" with { type: "json" };
+
+export const VERSION: string = pkg.version;
 
 export {
     Client,