Stream quiz JSON parsing on background executor

[MihaiCristianCondrea]

Summary

• Stream quiz_questions.json with JsonReader on a background ExecutorService and return results via callback
• Switch repository, use case, and view model to asynchronous callbacks
• Replace raw resource reads with buffered streams to avoid InputStream.available

Testing

• ./gradlew test (fails: SDK location not found)

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https://chatgpt.com/codex/tasks/task_e_68b703460bb8832d9c397852b8c82bfd