Preserve Workbench business rule payloads for clearer validation errors

[acwhite211]

Fixes #8045

Improve Workbench handling of back-end business rule validation errors. The back-end now preserves structured BusinessRuleException payloads in FailedBusinessRule upload results instead of stringifying and discarding them. The Workbench front-end uses those payloads to show uniqueness-rule failures and appends the conflicting record IDs when available. This makes duplicate catalog number errors clearer and avoids exposing raw Python exception tuples in validation tooltips.

Checklist

• Self-review the PR after opening it to make sure the changes look good and
  self-explanatory (or properly documented)
• Add relevant issue to release milestone
• Add pr to documentation list
• Add automated tests

Testing instructions

• Open a Workbench dataset that triggers a duplicate catalog number uniqueness error.
• Run validation.
• Hover or inspect the errored cell.
• Confirm the message reads like a normal validation error, for example Collectionobject must have unique catalognumber in collection.
• Confirm the message includes conflicting record IDs when provided, for example Conflicting record IDs: 3347460.
• Confirm the tooltip no longer shows the raw Python tuple/dict payload.

[coderabbitai]

Important

Review skipped

Draft detected.

Please check the settings in the CodeRabbit UI or the .coderabbit.yaml file in this repository. To trigger a single review, invoke the @coderabbitai review command.

⚙️ Run configuration

Configuration used: Organization UI

Review profile: CHILL

Plan: Pro Plus

Run ID: 60525d34-14cf-4528-99b0-033f38eb2186

You can disable this status message by setting the reviews.review_status to false in the CodeRabbit configuration file.

Use the checkbox below for a quick retry:

• 🔍 Trigger review

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch issue-8045

---

_{Comment @coderabbitai help to get the list of available commands and usage tips.}