Initial workspace scaffold

Cargo workspace with 5 crates: buh-entity (pure data structs),
buh-data (Turso/libsql data access), buh-util (scraper, rules,
processor, sync modules), buh-cli (binary "buh" with client/daemon
subcommands), and buh-ws (axum WebSocket server).

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

crates/buh-ws/Cargo.toml

@@ -0,0 +1,16 @@
+[package]
+name = "buh-ws"
+edition.workspace = true
+version.workspace = true
+
+[dependencies]
+buh-entity = { workspace = true }
+buh-data = { workspace = true }
+buh-util = { workspace = true }
+axum = { workspace = true }
+tokio = { workspace = true }
+serde = { workspace = true }
+serde_json = { workspace = true }
+anyhow = { workspace = true }
+tracing = { workspace = true }
+tracing-subscriber = { workspace = true }

crates/buh-ws/src/main.rs

@@ -0,0 +1,34 @@
+use axum::{
+    Router,
+    extract::ws::{WebSocket, WebSocketUpgrade},
+    response::IntoResponse,
+    routing::get,
+};
+
+async fn ws_handler(ws: WebSocketUpgrade) -> impl IntoResponse {
+    ws.on_upgrade(handle_socket)
+}
+
+async fn handle_socket(mut socket: WebSocket) {
+    while let Some(Ok(msg)) = socket.recv().await {
+        tracing::debug!(?msg, "received");
+        if socket.send(msg).await.is_err() {
+            break;
+        }
+    }
+}
+
+#[tokio::main]
+async fn main() -> anyhow::Result<()> {
+    tracing_subscriber::fmt()
+        .with_env_filter(tracing_subscriber::EnvFilter::from_default_env())
+        .init();
+
+    let app = Router::new().route("/ws", get(ws_handler));
+
+    let listener = tokio::net::TcpListener::bind("0.0.0.0:9000").await?;
+    tracing::info!("buh-ws listening on {}", listener.local_addr()?);
+    axum::serve(listener, app).await?;
+
+    Ok(())
+}