Fix debug message typo, replace process.exit with throws, fix test fixture naming

[Copilot]

Code review fixes across source and tests.

• src/zinc.ts — Remove extra )} in error debug template string producing garbled output
• src/utils.ts — Replace process.exit(-1) with proper error propagation so callers can handle failures; include supported content types in error message
• tests/utils/fixtures.ts, tests/engine.test.ts — Fix typo engineMartix → engineMatrix

Before (utils.ts):

} else {
  debug(`Unsupported content type: ${contentType}`);
  process.exit(-1);
}
} catch (err) {
  debug(`error when downloading and extracting the binary file: ${err}`);
  process.exit(-1);
}

After:

} else {
  throw new Error(`Unsupported content type: ${contentType}. Supported types: application/gzip, application/x-gzip, application/octet-stream, application/zip`);
}
} catch (err) {
  debug(`error when downloading and extracting the binary file: ${err}`);
  throw err;
}

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