fix: terminate worker threads after block evaluation in policy-service

[vshvets-bc]

Three policy blocks spawn worker_threads Workers via new Worker(...) but never call worker.terminate().
Node Worker threads do not auto-exit when the script body returns — they keep the V8 isolate alive (~30 MB each) waiting for more messages.
Every formula / custom-logic / data-transformation invocation leaked one worker thread. A heavy policy could accumulate multi-GB of leaked workers.

Adds a small cleanup() helper that calls worker.terminate() (with a swallowed .catch() for already-exited workers, e.g. via OOM-kill). Called on the terminating message, on error, and on every reject path.

• math-block.ts: terminate on the single 'done' message + on error
• custom-logic-block.ts (JS branch): terminate after the final 'done' (data.final === true) so debug messages are still forwarded for multi-emit custom-logic runs.
• data-transformation-addon.ts: terminate after final result + on error

Behavior unchanged for callers; resources are now released after each block evaluation.

[Pyatakov]

No 'exit' handler. Additional code block needs to be added in case if a worker exits without emitting 'done' and without emitting 'error' (e.g., process.exit(0) inside the worker, OOM-kill, or any unhandled internal throw that terminates the isolate)

Suggested change

	worker.on('exit', (code) => {
	cleanup();
	if (code !== 0 && code !== null) {
	reject(new Error(`Data transformation worker exited with code ${code}`));
	}
	});

[Pyatakov]

Please remove '/* noop */' here and in the two other places

[Pyatakov]

One-line comment is enough, please replace here and in the other two places with:
// Release the worker's V8 isolate; without this each invocation leaks ~30 MB.

[Pyatakov]

Suggested change

	const cleanup = () => { worker.terminate().catch(() => { /* noop */ }); };
	const cleanup = () => { worker.terminate().catch(() => {}); };
	worker.on('exit', (code) => {
	cleanup();
	if (code !== 0 && code !== null) {
	reject(new Error(`Math worker exited with code ${code}`));
	}
	});

[Pyatakov]

Suggested change

	const cleanup = () => { worker.terminate().catch(() => { /* noop */ }); };
	const cleanup = () => { worker.terminate().catch(() => {}); };
	worker.on('exit', (code) => {
	cleanup();
	if (code !== 0 && code !== null) {
	reject(new Error(`Custom logic worker exited with code ${code}`));
	}
	});