[Refactor] asHumanFriendlyArray to use flatMap

[gonzaloriestra]

WHY are these changes introduced?

Modernizes the asHumanFriendlyArray utility by replacing an imperative reduce implementation with a more declarative flatMap approach, improving readability and maintainability.

WHAT is this pull request doing?

• Refactors asHumanFriendlyArray in packages/cli-kit/src/public/common/array.ts to use flatMap.
• Adds comprehensive unit tests for asHumanFriendlyArray in packages/cli-kit/src/public/common/array.test.ts.

How to test your changes?

CI

Checklist

• I've considered possible cross-platform impacts (Mac, Linux, Windows)
• I've considered possible documentation changes
• I've considered analytics changes to measure impact
• The change is user-facing — I've identified the correct bump type (patch for bug fixes · minor for new features · major for breaking changes) and added a changeset with pnpm changeset add

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PR created automatically by Jules for task 9362088274305645564 started by @gonzaloriestra

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