fix(queue-events-producer): serialize object payloads as JSON

[mohanrajvenkatesan23-04]

Port Impact Checklist

• Python – does this change need to be ported or documented in the Python library?
• Elixir – does this change need to be ported or documented in the Elixir library?
• PHP – does this change need to be ported or documented in the PHP library?

Why

Fixes #2984.

QueueEventsProducer.publishEvent pushed each value of the payload straight onto the XADD args array. Redis then coerces every arg to a string via .toString(). For plain objects that yields "[object Object]", so a payload like { eventName: 'name', nested: { object: 'hello' } } arrived on the consumer side as { eventName: 'name', nested: '[object Object]' } — the original structure was unrecoverable.

The user reported the issue on src/classes/queue-events-producer.ts line 43 and noted that JSON serialization is the natural fix.

How

• src/classes/queue-events-producer.ts: when a value is a non-null object (plain object, array, class instance), JSON.stringify it before pushing onto the args array. Primitive values (strings, numbers, booleans) are left alone so existing publishers that already pass primitives observe no change.
• This mirrors what the producer already does conceptually for the built-in progress / completed events: their payloads round-trip through JSON.stringify on the producer side and JSON.parse on the consumer side (src/classes/queue-events.ts).
• The consumer side is intentionally not modified. Auto-parsing every value would risk mis-parsing user strings that happen to look like JSON. Consumers of object-typed custom events can call JSON.parse themselves on the field they expect.

Additional Notes (Optional)

• New regression test in tests/events.test.ts (when publishing custom events › serializes nested object payloads as JSON) publishes a { object: 'hello' } payload and asserts the receiver gets a JSON-string that parses back to the original object. Before the fix the test fails with '[object Object]'.
• No public API change; the type signature of publishEvent<T> is unchanged.
• TypeScript / Node-only. No port work required.

[manast]

@copilot resolve the merge conflicts in this pull request