[thxCode]

What type of PR is this?

/kind bug
/area testing

What this PR does / why we need it:

• Validate an existing release chart's index entry before a publication retry commits and deploys Pages.
• Use the workflow's pinned Helm 3.21 to parse the YAML index, then check the chart version, package URL filename and archive SHA-256 digest.
• Stop publication with an actionable error when the entry is missing or mismatched. Keep the existing archive and index bytes unchanged on a healthy retry.

Which issue(s) this PR links to:

Relates #707

Special notes for your reviewer:

• This follows the summary-only index finding on the merged publication PR. That PR merged before its review follow-up could land.
• The suggested grep-based condition would repackage an existing release archive; this guard preserves published package bytes.
• Ran the actual workflow step locally with the pinned Helm and published RC2 archive/index: healthy retry passed without chart-tree changes; missing entry, wrong digest, wrong package URL filename and wrong version all failed without changes. First publication also passed and retained all prior entries and archive bytes. No release tag was created.
• make generate, make lint, bash -n, and git diff --check passed. Actionlint passed after ignoring only its pre-existing unsupported concurrency.queue key, already accepted by the hosted workflow.
• No documentation tests were added. The updated workflow's hosted release retry remains to be exercised after merge.

Does this PR introduce a user-facing change?

NONE

[gpustack-code-review]

✅ OpenCodeReview: Review complete: 0 finding(s) across 1 selected item(s).

[thxCode]

Post-merge hosted verification passed: Site run 36705146473 retried the existing v0.9.0-rc2 publication using the merged workflow. The chart preparation/index guard, Pages deployment and public-content verification all succeeded.

The charts tree is byte-for-byte unchanged from the pre-retry snapshot. Public main identifies merge commit 7842ddb; RC2 retains its original tag revision and archive SHA-256 digest. No new release tag was created.