fix: skip destination transforms for explicit member maps (#952, ctor path)

[wyf027]

Summary

• Explicit .Map(...) configuration now takes precedence over global DestinationTransform rules such as EmptyCollectionIfNull
• Prevents explicit null member mappings from being overridden by collection transforms

Fixes#952

Test plan

• CI passes (WhenPerformingDestinationTransforms.Explicit_Null_Mapping_Is_Not_Overridden_By_EmptyCollectionIfNull)

[wyf027]

Updated 8b8898a: merged ctor-path fix from former #973 — ApplyDestinationTransform on record/class ctor args + explicit .Map skip in ApplyNullPropagationFromCtor. Added Explicit_Null_Record_Ctor_Mapping_Is_Not_Overridden_By_EmptyCollectionIfNull alongside existing property-map regression (#952). Covers both adapter and ctor instantiation paths.

[wyf027]

CI note: latest push 8b8898a — workflow still action_required (fork). Once Build and Test is approved, this covers both paths:\n- property mapping (BaseAdapter)\n- record/class ctor args (BaseClassAdapter + ApplyDestinationTransform)\n\nBuilds on #945 (#943) already on development.

[wyf027]

Batch ping: #966, #970, #971, #976, #979 (and other open fork PRs) are rebased on latest development (11853b3) and mergeable — all waiting on maintainer Build and Test workflow approval. Happy to address review feedback once CI runs.

[wyf027]

Open fork PRs (2026-05-27) — all rebased on development (11853b3), mergeable, awaiting Build and Test workflow approval:

PR	Type
#979	test (#938 UseDestinationValue)
#966	fix (#952 + ctor)
#970	fix (#900 MapToTarget)
#971	fix (#898 ProjectToType)
#976	fix (#947 MapWith cast)
#977	fix (#801 projection Include)
#965, #972	test-only

Happy to address review feedback once CI runs.