replace ContainerRuntime CLI to Bollard crate (default: docker socket)

limit tool result to open router tool response (with truncated info for
ai)

Hard kill if graceful shutdown is too long

.env.example

@@ -20,5 +20,5 @@ RUST_BACKTRACE=1
 METRICS_BIND_ADDR=
 
 # Sandboxed tool execution
-CONTAINER_RUNTIME=docker
+# DOCKER_HOST=
 SANDBOX_MAX_ITERATIONS=8