refactor(benchmark): replace whoami service with bench server

- Updated dev.compose.yml to define a new bench service that serves 4096 bytes of random data.
- Modified configurations for Traefik, Caddy, and Nginx to route traffic to the new bench service.
- Added Dockerfile and Go application for the bench server, including necessary Go modules.
- Updated benchmark script to target the new bench service endpoint.

cmd/bench_server/Dockerfile

@@ -0,0 +1,18 @@
+FROM golang:1.25.5-alpine AS builder
+
+HEALTHCHECK NONE
+
+WORKDIR /src
+
+COPY go.mod go.sum ./
+COPY main.go ./
+
+RUN go build -o bench_server main.go
+
+FROM scratch
+
+COPY --from=builder /src/bench_server /app/run
+
+USER 1001:1001
+
+CMD ["/app/run"]