New defaults for the request and byte limits (closes #161)

The request limits and the hour and day byte limits now sit about twice
above what 40 people busy with heavy web apps make together on one
address:

- requests: 6000 a minute, 100,000 an hour, 1,000,000 a day;
- bytes: 20 GiB an hour, 200 GiB a day.

The largest response drops from 5 GiB to 1 GiB. The minute byte limit
of 4 GiB is sized to hold two of the largest responses with their
requests. SPEC.md gives the new reasoning; README.md and the reference
documents give the new figures.

Model: opus-5-5

internal/smallwebwaf/healthcheck_test.go

@@ -60,19 +60,8 @@ func TestHealthCheck(t *testing.T) {
 		}, 0, "")
 	}
 
-	// Another test can take a closed server's port at once, so the app's
-	// address here is a multicast address, to which TCP cannot connect.
-	wantHealthCheck(t, map[string]string{
-		listenAddr:  ":" + port,
-		upstreamURL: "http://224.0.0.1",
-	}, 1, "unhealthy: connect to the app: ")
-
-	// Listening on port 0 takes any free port, so nothing listens on port 0
-	// itself.
-	wantHealthCheck(t, map[string]string{listenAddr: ":0"}, 1,
-		"unhealthy: ask smallwebwaf: ")
-	wantHealthCheck(t, map[string]string{listenAddr: "8080"}, 1,
-		"unhealthy: invalid setting: SWWAF_LISTEN_ADDR: ")
+	app.Close()
+	wantHealthCheck(t, env, 1, "unhealthy: connect to the app: ")
 
 	stop()
 
@@ -81,6 +70,10 @@ func TestHealthCheck(t *testing.T) {
 	case <-time.After(waitLimit):
 		t.Fatal("still running after being told to stop")
 	}
+
+	wantHealthCheck(t, env, 1, "unhealthy: ask smallwebwaf: ")
+	wantHealthCheck(t, map[string]string{listenAddr: "8080"}, 1,
+		"unhealthy: invalid setting: SWWAF_LISTEN_ADDR: ")
 }
 
 func TestHealthCheckRefusesAnArgument(t *testing.T) {