task: update documentation for v26.1.2

[e0ne]

No description provided.

[greptile-apps]

Greptile Summary

Updates the documentation for the v26.1.2 general-availability release.

• Replaces release-candidate tags and staging repositories with production image references.
• Updates image digests and supported DOCA-OFED driver tags.
• Aligns documented Helm defaults with the v26.1.2 release images.

Confidence Score: 5/5

The documentation-only release update appears safe to merge.

The changed version, repository, and image-tag references are internally consistent across the shared variables, image inventory, and Helm defaults, with no concrete blocking failure identified.

Important Files Changed

Filename	Overview
docs/advanced/images-sha256.rst	Updates Network Operator and DOCA-OFED image repositories, tags, platform variants, and digests for v26.1.2.
docs/common/vars.rst	Advances shared release substitutions from the release candidate to v26.1.2 production versions and repositories.
docs/customizations/helm.rst	Updates documented Helm image defaults to match the v26.1.2 production release.

_{Reviews (1): Last reviewed commit: "task: update documentation for v26.1.2" | Re-trigger Greptile}

[rollandf]

Not needed anymore, see #405