fix: handle CLI metadata flags before auth

[xianzuyang9-blip]

Summary

• handle --version / -v and --help / -h before starting FastMCP/authentication
• print package version/help and exit cleanly without requiring Firecrawl credentials
• leave normal server startup unchanged when no metadata flag is present

Fixes #256.

Reproduction

Current published package fails metadata flags without Firecrawl env:

npx --yes firecrawl-mcp@3.20.2 --version
Either FIRECRAWL_API_KEY or FIRECRAWL_API_URL must be provided

npx --yes firecrawl-mcp@3.20.2 --help
Either FIRECRAWL_API_KEY or FIRECRAWL_API_URL must be provided

Validation

npm install
npm run build
node dist/index.js --version   # 3.20.2
node dist/index.js --help      # prints help, exits 0
node dist/index.js -h          # prints help, exits 0

npm test -- --runInBand currently cannot start because jest is not installed by this package's devDependencies (Cannot find module ... node_modules/jest/bin/jest.js), so I used the focused build + CLI checks above for this CLI metadata fix.