Stream large uploads and add stress tests

[DevOpsMadDog]

Summary

• stream ingestion uploads into disk-backed buffers and persist artefacts without storing full payloads in memory
• harden normalizer byte handling to read chunked streams and reset file pointers for decompression
• add end-to-end stress tests for spooled compressed uploads and offline normalizer coverage

Testing

• pytest tests/test_end_to_end.py

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https://chatgpt.com/codex/tasks/task_e_68e1bdcee3988329ac7d6d424ba7d40f