🧹 [Refactor nested networking operations]

[Tcode-Motion]

🎯 What: Extracted the massive inline closures for TCP operations (tcp_listen, tcp_connect, tcp_send, tcp_recv) from stdlib/src/net.rs into a dedicated standalone file stdlib/src/net_handler.rs.
💡 Why: Reduces module registration footprint, improves code readability, and makes the networking logic easier to maintain and test by adhering to standard handler patterns.
✅ Verification: Verified by compiling the project, running cargo test --workspace --all-targets (noting pre-existing bincode compilation failure but ensuring no new errors were introduced by the refactor itself).
✨ Result: A cleaner module definition in net.rs and better organized code.

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PR created automatically by Jules for task 8418938339376718434 started by @Tcode-Motion

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