EPIC: Implement Node.js LLM Router Middleware

[mrnicholasbcarter-code]

Match the TypeScript Node.js interceptor seamlessly to the Python LLM-Gate router logic.

Acceptance Criteria:

• Create rigorous Zod schemas for all payload validations.
• Ensure compatibility natively with Express and Next.js /api routes.
• Document the fail-open fallback behavior cleanly.

[mrnicholasbcarter-code]

Epic complete in PR #28; Next.js /api compatibility and explicit fail-open docs added, all CI passed.

[mrnicholasbcarter-code]

Completed via PR #28 (merge ). Added Next.js /api handler compatibility and explicit fail-open fallback documentation. CI passed; 158 tests locally.

[mrnicholasbcarter-code]

Evidence correction: PR #28 merged as 0e0154d. Added Next.js /api handler compatibility and explicit fail-open fallback documentation. CI passed; 158 tests locally.