feat(retail): add searchOffset, searchPagination, and searchRequest samples

[angelcaamal]

Description

Fixes Internal: b/502273843
Note: Before submitting a pull request, please open an issue for discussion if you are not associated with Google.

Checklist

• I have followed guidelines from CONTRIBUTING.MD and Samples Style Guide
• Tests pass: npm test (see Testing)
• Lint pass: npm run lint (see Style)
• Required CI tests pass (see CI testing)
• These samples need a new API enabled in testing projects to pass (let us know which ones)
• These samples need a new/updated env vars in testing projects set to pass (let us know which ones)
• This pull request is from a branch created directly off of GoogleCloudPlatform/nodejs-docs-samples. Not a fork.
• This sample adds a new sample directory, and I updated the CODEOWNERS file with the codeowners for this sample
• This sample adds a new sample directory, and I created GitHub Actions workflow for this sample
• This sample adds a new Product API, and I updated the Blunderbuss issue/PR auto-assigner with the codeowners for this sample
• Please merge this PR for me once it is approved

Note: Any check with (dev), (experimental), or (legacy) can be ignored and should not block your PR from merging (see CI testing).

[snippet-bot]

Here is the summary of changes.

You are about to add 3 region tags.

• retail/snippets/searchOffset.js:17, tag retail_v2_search_offset
• retail/snippets/searchPagination.js:17, tag retail_v2_search_pagination
• retail/snippets/searchRequest.js:17, tag retail_v2_search_request

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[gemini-code-assist]

Code Review

This pull request introduces Node.js snippets for Google Cloud Retail search features, including offset-based search, paginated search, and general search requests, along with a comprehensive test suite. The review feedback highlights opportunities to improve test robustness against existing data, ensure consistency across snippets by adding missing strict mode directives, and standardize logging and error handling patterns.