fix: add ORDER event type to AssetEventType enum

[MuhammadMinhaj]

The OpenSea REST API returns event_type "order" for listing events, but the SDK enum only had "listing". This caused listing events to fall through unhandled when consuming real API responses.

Added ORDER = "order" to AssetEventType. LISTING is kept for backwards compatibility. No breaking changes.

Motivation

The OpenSea Events API (/api/v2/events) returns event_type: "order" for listing events in real API responses. The SDK's AssetEventType enum only defined "listing", causing a mismatch where listing events were silently unhandled when processing live API data.

Solution

Added ORDER = "order" to the AssetEventType enum. LISTING is retained for backwards compatibility. This is a purely additive change with no breaking changes.

[ryanio]

Thanks for identifying this gap @MuhammadMinhaj! The API does indeed return event_type: "order" in responses.

We've opened #1929 which builds on your change with a couple of additions:

• Added a corresponding OrderEvent response type (with asset optional for collection/trait offers, criteria optional, and order_type field)
• Added OrderEvent to the AssetEvent union so consumers can properly type-narrow
• Noted that "order" is a response-only value (the API query filter accepts the specific types like listing, offer, etc.)

You're credited as co-author on the commit. Closing in favor of #1929.

[MuhammadMinhaj]

Thanks for the update and improvements! Appreciate the co-author credit. 🙌