[FEATURE] Make sandbox builds reproducible by pinning tool versions #1266

Summary

The Strix sandbox image does not resolve the same declared inputs every time it is built from the same commit

Its Dockerfile uses rolling images, latest package versions, and remote installer scripts without fixed artifacts

This weakens reproducibility, reviewability, and incident response for the environment that runs security tools against user targets

Moving parts in the current build

The current containers/Dockerfile includes these inputs

• The base image is kalilinux/kali-rolling:latest in both build stages
• Several Go tools installed with @latest
• Several npm tools installed with @latest
• The uv shell installer without a pinned release artifact
• The latest Gitleaks release selected at build time
• The Trivy installer without a pinned version

Recommendation

Pin the Kali base image by digest and pin every directly installed Go, npm, Python, and downloaded tool version

Downloaded artifacts should have checksum verification, and the finished image should include a machine-readable inventory of its tools and versions

Dependency updates can then happen through explicit reviewable commits followed by smoke tests for both supported architectures

Relationship to existing work

Pull request #960 contains related publishing, SBOM, and provenance work

This issue covers the mutable inputs that remain inside the Dockerfile

The end result should let maintainers rebuild the same declared inputs from the same commit and let users select the runtime image by digest