compiler: make include manifest ordering deterministic

[davidahmann]

Problem

Lock header output can drift in non-semantic ways when IncludedFiles are emitted in input order, creating noisy diffs.

What changed

• Canonicalized IncludedFiles rendering in workflow header generation.
• Preserved existing topological ordering for ImportedFiles (dependency-order contract).
• Added/updated header helper coverage to assert deterministic include ordering.

Validation

• make fmt
• go test ./pkg/workflow -run TestGenerateWorkflowHeader -count=1
• go test ./pkg/workflow -run TestImportOrdering -count=1
• make test-unit (fails in this local macOS env due unrelated baseline shell compatibility in TestGitPatch* using ${var@Q} in bash script fixtures)

Refs #16095

[davidahmann]

Implemented deterministic manifest output for include entries while preserving import dependency ordering.

Scope in this PR:

• Canonicalized IncludedFiles emission in workflow headers.
• Kept ImportedFiles topological order intact.
• Added regression coverage for deterministic include ordering.

This contribution was informed by patterns from Gait: https://github.com/davidahmann/gait

[pelikhan]

Could you merge main?

[pelikhan]

Restarted in #16138