Wizard: prevent duplicate languages in Locale step (HMS-10599)

[mgold1234]

replaceLanguage did not guard against duplicates, and LanguageRow
used key={lang} which caused React warnings when duplicates arrived
from an imported blueprint.

• Add duplicate guard to replaceLanguage
• Fix list key to handle duplicate entries
• Add tests for duplicate language validation

Why is this needed?

The duplicate language validation and error message were already
implemented in a previous commit, but had no test coverage.
Additionally, replaceLanguage did not prevent creating duplicates
at the reducer level, and React would log warnings about duplicate
keys when a blueprint with duplicate languages was loaded from the API.

These changes harden the existing validation by preventing duplicates
at the source and ensuring the rendering handles them gracefully.

To reproduce

Create a blueprint via API with duplicate languages:

fetch('/api/image-builder/v1/blueprints', {
  method: 'POST',
  headers: { 'Content-Type': 'application/json' },
  body: JSON.stringify({
    name: "test-duplicate-languages",
    distribution: "rhel-9",
    image_requests: [{ architecture: "x86_64", image_type: "guest-image",
      upload_request: { type: "aws.s3", options: {} } }],
    customizations: { locale: { languages: ["en_US.UTF-8", "en_US.UTF-8", "C.UTF-8"] } }
  })
}).then(r => r.json()).then(console.log)

Then open the blueprint in the wizard — the Locale step shows
"Duplicated languages: en_US.UTF-8" and blocks the Next button.

JIRA: HMS-10599

[codecov]

Codecov Report

❌ Patch coverage is 83.33333% with 1 line in your changes missing coverage. Please review.
✅ Project coverage is 75.64%. Comparing base (6044553) to head (4216b54).
⚠️ Report is 7 commits behind head on main.

Files with missing lines	Patch %	Lines
...zard/steps/Locale/components/LanguagesDropDown.tsx	83.33%	1 Missing ⚠️

@@            Coverage Diff             @@
##             main    #4527      +/-   ##
==========================================
+ Coverage   75.62%   75.64%   +0.01%     
==========================================
  Files         250      249       -1     
  Lines        7159     7152       -7     
  Branches     2655     2655              
==========================================
- Hits         5414     5410       -4     
+ Misses       1503     1500       -3     
  Partials      242      242              

Files with missing lines	Coverage Δ
...zard/steps/Locale/components/LanguagesDropDown.tsx	92.98% <83.33%> (+4.09%)	⬆️

... and 3 files with indirect coverage changes

---

Continue to review full report in Codecov by Harness.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 6044553...4216b54. Read the comment docs.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.
• 📦 JS Bundle Analysis: Save yourself from yourself by tracking and limiting bundle sizes in JS merges.

[sourcery-ai]

Hey - I've left some high level feedback:

• Using index as part of the React key in LanguagesDropDown can still cause subtle rendering bugs when items are reordered or removed; consider using a stable key such as ${lang}-${occurrenceIndex} where occurrenceIndex is derived from counting occurrences of the same language up to that point.
• In replaceLanguage, the duplicate guard logic is a bit dense; extracting the isDuplicate check into a small helper function (with a short comment explaining the oldLanguage exception) would make the intent clearer and reduce chances of future regressions when this logic is modified.

Prompt for AI Agents

Please address the comments from this code review:

## Overall Comments
- Using `index` as part of the React key in `LanguagesDropDown` can still cause subtle rendering bugs when items are reordered or removed; consider using a stable key such as `${lang}-${occurrenceIndex}` where `occurrenceIndex` is derived from counting occurrences of the same language up to that point.
- In `replaceLanguage`, the duplicate guard logic is a bit dense; extracting the `isDuplicate` check into a small helper function (with a short comment explaining the `oldLanguage` exception) would make the intent clearer and reduce chances of future regressions when this logic is modified.

---

Sourcery is free for open source - if you like our reviews please consider sharing them ✨

• X
• Mastodon
• LinkedIn
• Facebook

_{Help me be more useful! Please click 👍 or 👎 on each comment and I'll use the feedback to improve your reviews.}

[kingsleyzissou]

Looks good. I added some nitpicks inline, but we could do those in a follow up.