ci: move bioflow ci into nix checks

[midischwarz12]

Summary

• replace repo-local BioFlow CI with shared Nix CI caller
• move build, checks, golden verification, demo, autopilot, and package smoke coverage into the flake
• replace local conventional commit and CLI release workflows with shared workflow callers

Validation

• nix build .#bioflow -L
• nix build .#checks.x86_64-linux.golden-node20 -L
• nix build .#checks.x86_64-linux.golden-node22 -L
• nix build .#checks.x86_64-linux.package-smoke -L
• nix build .#checks.x86_64-linux.demo-killer -L
• nix build .#checks.x86_64-linux.cli-autopilot-flow -L
• nix flake check -L
• actionlint .github/workflows/ci.yml .github/workflows/conventional-commits.yml .github/workflows/release-cli.yml