feat(ws): extend TradeMessage with full trade execution fields

TradeMessage was severely under-specified compared to the Polymarket WS
API. Add missing fields needed by the engine: taker_order_id,
maker_orders, trader_side, fee_rate_bps, outcome, owner, trade_owner,
transaction_hash. Replace untyped status/msg_type strings with proper
TradeMessageStatus and TradeMessageType enums.

examples/demo.rs

@@ -623,11 +623,19 @@ impl PolyfillDemo {
                 side: Side::BUY,
                 size: dec!(50.0),
                 price: dec!(0.75),
-                status: Some("MATCHED".to_string()),
+                status: TradeMessageStatus::Matched,
                 msg_type: None,
                 last_update: None,
                 matchtime: None,
                 timestamp: None,
+                outcome: None,
+                owner: None,
+                trade_owner: None,
+                taker_order_id: None,
+                maker_orders: vec![],
+                fee_rate_bps: None,
+                transaction_hash: None,
+                trader_side: None,
             }),
         ];