Sync OSS release snapshot

[keshprad]

Summary

• Refresh the existing OSS snapshot branch from internal release/oss-2026-07-21 at 40a7657.
• Add the public-safe CHANGELOG.md for version 2.4.2; it contains no internal GitLab URLs or commit links.
• Preserve OSS boundaries: release tooling, the internal NVIDIA Inference provider, and tests that require either remain excluded. No new package release was created.

Verification

• Internal pipeline: lint, unit, integration, and Sonar passed; only the optional manual provider job remains.
• Public make lint and make format-check passed.
• Public make test-unit: 1,386 passed, 34 deselected, 6 xfailed.
• GitNexus: both omitted internal-only tests had low, zero-caller impact; staged public changelog change has no code-symbol impact.
• Public diff checks passed; GitHub workflows are unchanged.