Make ranking engine package consumable

[gnanirahulnutakki]

Summary

• switch @ardurai/contracts to the public HTTPS archive pin so consumers do not need SSH git access
• add a build-specific TypeScript config that excludes tests from packaged dist
• commit runtime dist output required by the package exports in GitHub archive installs
• add prepack and test:package smoke coverage for local pack/install/import

Validation

• npm ci
• npm test (97 pass)
• npm run typecheck
• npm run build
• npm run test:package
• npm audit --audit-level=high
• git diff --check
• semgrep scan --config auto --error scripts/package-smoke.mjs package.json

Dependency note

This is required before ardur.ai INTEG-003 can consume @ardurai/ranking-engine from a GitHub archive. Current main installs but fails to import because dist/index.js is missing from the archive.