fix(zmq): use JSON on wire, accept JSON keywords in parser

[avinxshKD]

Java's ZMQ write() was serializing with toPythonLiteral(), so booleans/null came out as True/False/None. Python's recv_json() calls json.loads() under the hood, which rejects that. Pure-numeric payloads worked by accident; anything with a boolean or null silently broke.

Same issue in reverse: Python's json.dumps() sends true/false/null, and the Java parser only knew True/False/None, throwing IllegalArgumentException on receipt

Fix

• Added toJsonLiteral() (mirrors toPythonLiteral(), JSON values instead of Python ones) and swapped it in for the ZMQ write() path only, file I/O unchanged.

• Extended parseKeyword() to accept true/false/null alongside the Python variants, so the parser handles both formats.

Tests

Added testJsonKeywordTrue/False/Null, testJsonMixedList, testJsonRoundTrip to TestLiteralEval.

closes #492

[avinxshKD]

Hey @pradeeban also after a sim finishes I keep going back to manually check the port files, would a concore export CLI command to dump edge data to CSV make sense? could wire it into the existing CLI like watch #450. Let me know if that's worth working on