Harden token alignment and source-build acquisition

[fly1d]

Summary

• enforce a strict token bijection for TypeScript and Rust model output
• make the currently available source build the primary product-page action
• provide a complete macOS first-translation path and verify Node 22.13 compatibility
• label the signed beta as an up-to-15-user waitlist and track Hashnode applications

Review

• independent review found and resolved Node/macOS compatibility, waitlist policy, and Rust parity gaps
• no unresolved findings remain

Verification

• npm run check
• npm run test:smoke
• npm run test:site
• npm run desktop:check
• Node 22.13.0: typecheck, 14 Vitest tests, and production build
• desktop and 390px mobile screenshots reviewed in Chinese and English