[TyceHerrman]

The existing nixpkgs pin produces or-as-identifier deprecation warnings with Lix 2.95. This updates nixpkgs and bash-env-json, fixes the assertion imports needed by current Nushell, and updates CI to Nushell 0.116.1 and bash-env-json 0.11.0.

The bash-env-json update brings in its directory variable filtering and _error_file leak fixes. Its removal of flake-utils also removes the corresponding transitive lockfile entries. Both test files now import std/assert, and the workflow's download URLs and PATH assignment are quoted to address the existing ShellCheck findings.

The README now documents migration from deprecated --export to --shellvars, including selecting individual shell variables and merging them with environment changes to preserve the previous output shape. The existing --export tests remain as compatibility coverage.

The changes are split into four commits for dependency pins, assertion imports, CI updates, and README deprecation info update.

Validation (macOS ARM64 host):

• Nix development shell loads with Nushell 0.116.1, Bash 5.3.15, and jq 1.8.2, without the or-as-identifier warnings.
• nix build --no-link .#default passes.
• All 12 tests pass against the source module with the exact bash-env-json 0.11.0 release used by CI.
• All 12 tests also pass against the Nix-built module.
• actionlint .github/workflows/test-suite.yml, including ShellCheck, passes with no findings.
• Diff whitespace checks pass.
• Verified both README migration examples with Nushell 0.116.1 and bash-env-json 0.11.0, including checking that the merged result matches --export [A].
• Test suites passed in an Ubuntu container.

[tesujimath]

Thanks!