[clowders]

Update nullkomma from 0.1.536 to 0.1.552 (b6971c3), the latest released main revision at the start of this upgrade.

Remove the Linux Chromium font wrapper, the elf-specific startup setup hook, and the explicit allowOffNixpkgs opt-in. Upstream now provides each behavior through dataheld/nullkomma#260, dataheld/nullkomma#263 and dataheld/nullkomma#262. flake.nix shrinks from 94 to 69 lines; only flake.nix and flake.lock change. Applying the upstream upgrade workflow produced no additional tracked-file changes.

Closes #54.

Reviewed issues, PRs and discussion updated in both repositories during the preceding 12 hours. Keep #55 pending dataheld/nullkomma#258, and #52/#53 pending dataheld/nullkomma#264 (still open). Preserve the serial worker limit tracked by #56, browser preflight, timeouts, snapshots, check arguments and current CI/deployment gating. Neither #57 nor #62 is fixed by these upstream releases.

Validation:

• nix develop --command tasks all
• nix flake check --print-build-logs
• nix flake check --all-systems --build-all --print-build-logs: all exported checks, websites, deployment packages and development shells pass on aarch64-darwin, aarch64-linux and x86_64-linux.
• Installed-package browser suites pass on local macOS and both Linux architectures: 46 passes each, zero failures/warnings, only the four existing fixture-setup skips. Snapshots and comparison thresholds are unchanged.

Hosted CI and live deployment were not run. The signed commit uses [skip ci] to avoid duplicate expensive builds. The existing macOS sandbox browser exclusion remains; the installed suite was executed separately as the login user.