fix(ws): add trigger fields to BasicOrder websocket updates

[knoal]

Summary

• add the missing trigger/order metadata fields to websocket BasicOrder
• align websocket BasicOrder more closely with REST BasicOrderInfo
• add deserialization tests covering trigger-order payloads and null tif

What changed

src/ws/sub_structs.rs

• added:
  • trigger_condition: String
  • is_trigger: bool
  • trigger_px: String
  • is_position_tpsl: bool
  • reduce_only: bool
  • order_type: String
  • tif: Option<String>

Why

WebSocket OrderUpdate payloads were missing fields that are already present in REST BasicOrderInfo, which made it hard to identify trigger orders and inspect TP/SL-related metadata from real-time order updates alone.

This brings websocket order updates in line with the data already available through REST and avoids forcing consumers to poll for order details.

Validation

• cargo fmt
• cargo test
• cargo clippy -- -D warnings

Closes #192