🔒 Fix DoS via unbounded IPFS file parsing

[scobru]

🎯 What: Added a 5MB size limit to memory buffering in IPFS API endpoints.
⚠️ Risk: An attacker or a malicious IPFS peer could serve an excessively large payload. This would cause the Node.js server to read unbounded data into memory, potentially blocking the event loop or causing Out-Of-Memory (OOM) crashes (Denial of Service).
🛡️ Solution: Implemented a `MAX_JSON_SIZE` constant limit. If the accumulated chunks exceed this limit during an incoming request, the server sets a flag, immediately destroys the connection, and returns a `413 Payload Too Large` HTTP response.

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PR created automatically by Jules for task 15597975954597844808 started by @scobru

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