feat(utils): add version retrieval utility

- Introduces a function to retrieve the application version
- Returns 'dev' if the version file is missing and 'unknown' for other errors
- Exports the new utility for use in other modules

src/utils/mod.ts

@@ -1,2 +1,3 @@
 export { resolveUnitTargetPath, writeUnitFiles } from './fs.ts';
 export { deriveNameFromExec } from './misc.ts';
+export { getVersion } from './version.ts';