Handle BrowserStack MCP metadata flags

[wowsofine]

Summary

• handle --version/-v and --help/-h before credential validation
• keep metadata flags usable without BROWSERSTACK_USERNAME or BROWSERSTACK_ACCESS_KEY
• add a Vitest coverage path for the no-credential metadata flags

Reproduction

npm exec --yes --package=@browserstack/mcp-server@1.2.20 -- browserstack-mcp-server --version currently prints a BROWSERSTACK_USERNAME environment variable error instead of version metadata. The same credential check also blocks --help.

Validation

• Red test first: new metadata tests failed because stdout was empty and credential validation ran first
• npx vitest run tests/cli-metadata.test.ts
• npm test (22 files, 184 tests)
• npm run lint
• npx tsc --noEmit
• npm run build
• local npm pack + npm exec --package=<tarball> -- browserstack-mcp-server --version prints 1.2.21
• local npm pack + npm exec --package=<tarball> -- browserstack-mcp-server --help
• git diff --check