#116: Python 3.12 support and exatest cleanup

[tkilias]

Summary

• Upgrade the project to Python 3.12 across packaging, CI, and test tooling.
• Update the UDF debug path for Python 3.12 compatibility.
• Remove the obsolete exatest server stack and related test helpers, including FTP, SMTP, HTTP, MessageBox, and the standalone threading helper.
  • The server can replace in the SLC repos by either stdlib implementations (simple network tests) or using the UDFDebugger (cleanup and init)
• Keep the remaining exatest surface focused on the UDF-related pieces still used by the test framework.

Validation

• limactl shell default with Poetry on Python 3.12
• nox -s lint
• Integration tests executed against the ITDE docker-db in Lima
• FTP, SMTP, UDF debug, and docker-db environment checks passed before the server cleanup

Closes #116

[sonarqubecloud]

Quality Gate failed

Failed conditions
0.0% Coverage on New Code (required ≥ 80%)
C Security Rating on New Code (required ≥ A)

See analysis details on SonarQube Cloud

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[kratz00]

Suggested change

	* Python 3.10, 3.11, and 3.12
	* Python 3.10, 3.11 and 3.12