feat: attestation, FUSA-STUB001/002 detection, and coverage-gate wiring - #85

Node.js 20 is deprecated. The following actions target Node.js 20 but are being forced to run on Node.js 24: github/codeql-action/analyze@v3, github/codeql-action/init@v3. For more information see: https://github.blog/changelog/2025-09-19-deprecation-of-node-20-on-github-actions-runners/

Expected `which go` to return /home/runner/work/_temp/codeql-action-go-tracing/bin/go, but got /opt/hostedtoolcache/go/1.22.12/x64/bin/go: please ensure that the correct version of Go is installed before the `codeql-action/init` Action is used.