ci: test build across supported Node versions

[DorianChn]

Summary

• use npm ci so CI validates the committed lockfile
• test the supported Node 20 and Node 22 runtimes
• build the TypeScript distribution and smoke-test the generated CLI

Validation

• npm ci --dry-run --ignore-scripts --no-fund --no-audit
• npm run build
• npm run typecheck
• npm test -- --run (59 tests passed)
• node dist/cli.js --help
• git diff --check

[DorianChn]

Added commit 7d66118: invalid answer.matches and tool.args.matches regexes now produce failed assertions with clear messages instead of throwing; tool.args also validates that equals or matches is present. Verified with npm test (62 passed) and npm run build.

[DorianChn]

Independent validation against current main:

• npm ci --ignore-scripts --no-fund --no-audit ✅
• npm run typecheck ✅
• npm test -- --run ✅ 59 tests / 6 files
• npm run build ✅
• npm audit --audit-level=high ✅ 0 vulnerabilities (using a temporary npm cache; default cache had a local write error)
• working tree clean ✅

GitHub currently reports no checks for this branch, so these are local results only. PR #5 remains the existing CI/build improvement PR and is conflict-free.