Add websocket4java to Networking

[tuyucheng777]

Adds WebSocket4Java, High-performance WebSocket framework based on JDK NIO and virtual threads, with zero third-party dependencies at runtime.

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Summary by cubic

Adds WebSocket4Java to the networking libraries list in README_SOURCE.md, highlighting its high-performance WebSocket framework built on JDK NIO and virtual threads with zero runtime dependencies.

^{Written for commit 060d1a2. Summary will update on new commits.}

[cubic-dev-ai]

No issues found across 1 file

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