feat: add JavaScript implementation of ngwaf-compute-interface

[Copilot]

Summary

Creates a JavaScript Fastly Compute implementation of the existing Rust ngwaf-compute-interface service in a new ngwaf-compute-interface-javascript/ directory, using version 3.40.1 of the @fastly/js-compute SDK.

Changes

• src/index.js – Main entry point implementing the same logic as the Rust service:
  • Validates cdn-secret header (returns 403 if missing/wrong)
  • Reads corp and workspace from the ngwaf Config Store
  • Optionally overrides client IP from the x-source-ip header
  • Calls inspect() from fastly:security
  • Returns a JSON body and waf-info header with decision time, request ID, agent response, tags, and verdict
  • Status code is passed through if in 200–499 range, otherwise returns 500
• package.json – Declares @fastly/js-compute@3.40.1 as a dev dependency with build and deploy scripts
• fastly.toml – JavaScript compute manifest with the same ngwaf config store setup (including local server defaults) as the Rust version
• README.md – Full documentation mirroring the Rust README
• .gitignore – Ignores bin/ and node_modules/

Testing

The project builds successfully with npm run build (compiles to WASM via js-compute-runtime).

[BrooksCunningham]

@rabdelazim Can you review this implementation?