C3: add a read timeout and message-size limits to the Binance stream

connect() used connect_async with no WebSocketConfig and next_event
awaited the socket with no deadline, so a stalled server hung the feed
forever and an oversized message could force an unbounded allocation.
connect() now passes a WebSocketConfig capping message/frame size, and
next_event wraps the read in a 300s tokio timeout (well above Binance's
~3-minute ping), surfacing a stall as the new Error::Timeout.

crates/wickra-data/src/error.rs

@@ -20,6 +20,10 @@ pub enum Error {
     #[error("malformed payload: {0}")]
     Malformed(String),
 
+    /// A live-feed read exceeded its deadline.
+    #[error("read timed out")]
+    Timeout,
+
     #[cfg(feature = "live-binance")]
     #[error("websocket error: {0}")]
     WebSocket(#[from] tokio_tungstenite::tungstenite::Error),