fix: generate a cross-platform test command for TS ESM apps

[TibJnt]

Summary

• use cross-env in the generated TypeScript ESM npm test script so the template works on Windows
• add generator assertions that the template includes cross-env and still preserves the expected test glob

Problem

Issue #835 reports that generated --lang=ts --esm apps emit FASTIFY_AUTOLOAD_TYPESCRIPT=1 node ... in package.json, which breaks on Windows because inline environment variable assignment is shell-specific.

Validation

• node suite-runner.js "test/generate-typescript.test.js"
• node suite-runner.js "test/generate-typescript-esm.test.js"

Notes

• The branch was pushed via the existing SSH fork remote.
• The repo-level npm test command currently hits an unrelated Node 26 / yargs ESM failure in the existing suite.