Give every API value with a unit as a number (closes #199)

A value with a unit is now a number, and its field name ends in the
unit, as the vendored API_POLICIES.md requires. @meta.execution_time
becomes execution_time_ms. In the stats answers, uptime,
connection_duration, memory_usage and whois_stats.current_interval
become uptime_seconds, connection_duration_seconds, memory_usage_bytes
and whois_stats.current_interval_seconds. connection_duration_seconds
is null while the feed is not connected. The status page formats the
numbers itself. REPO_POLICIES.md is re-vendored from the same
sneak/prompts commit.

Model: opus-5-5

internal/server/middleware_internal_test.go

@@ -10,6 +10,7 @@ import (
 	"net/http/httptest"
 	"net/netip"
 	"os"
+	"regexp"
 	"strings"
 	"testing"
 	"time"
@@ -100,6 +101,81 @@ func TestJSONValidationKeeps4xxWithoutBody(t *testing.T) {
 	checkJSONErrorMessage(t, name, rec, http.StatusText(http.StatusBadRequest))
 }
 
+// TestJSONAnswersPutNoUnitInAString sends a request to each JSON route and
+// checks each answer. Its @meta.execution_time_ms is a number, and none of its
+// strings is a number with a unit, such as "12 ms", "1.1 GB" or "1h18m34s"
+// (https://git.eeqj.de/sneak/routewatch/issues/199). The health check answers
+// 503, since the stream is not connected, and the last path matches no route.
+func TestJSONAnswersPutNoUnitInAString(t *testing.T) {
+	t.Parallel()
+
+	numberWithUnit := regexp.MustCompile(
+		`^([0-9]+(\.[0-9]+)? ?(ns|µs|ms|s|m|h|B|kB|MB|GB|TB))+$`)
+
+	s := newServerWithTestRoutes(t)
+	s.resolver = &fakeResolver{}
+	s.SetASNFetcher(fixedIntervalASNFetcher{interval: time.Second})
+
+	paths := []string{
+		statusJSONPath,
+		statsPath,
+		"/.well-known/healthcheck.json",
+		"/api/v1/ip/" + untrustedPeerAddr,
+		"/ip/" + untrustedPeerAddr,
+		asJSONPath,
+		"/api/v1/prefix/" + testPrefixV4,
+		"/api/v1/search/as?q=google",
+		"/api/v1/no-such-route",
+	}
+
+	for _, path := range paths {
+		rec := httptest.NewRecorder()
+		s.router.ServeHTTP(rec, httptest.NewRequestWithContext(
+			t.Context(), http.MethodGet, path, nil))
+
+		var answer map[string]any
+
+		err := json.Unmarshal(rec.Body.Bytes(), &answer)
+		if err != nil {
+			t.Errorf("%s: decoding the answer: %v; answer %s", path, err, rec.Body)
+
+			continue
+		}
+
+		meta, _ := answer["@meta"].(map[string]any)
+		if _, ok := meta["execution_time_ms"].(float64); !ok {
+			t.Errorf("%s: @meta.execution_time_ms is not a number: %s",
+				path, rec.Body)
+		}
+
+		for _, value := range stringsIn(answer) {
+			if numberWithUnit.MatchString(value) {
+				t.Errorf("%s: %q is a number with a unit in a string", path, value)
+			}
+		}
+	}
+}
+
+// stringsIn returns every string in a decoded JSON value, at any depth.
+func stringsIn(value any) []string {
+	var found []string
+
+	switch v := value.(type) {
+	case string:
+		found = append(found, v)
+	case []any:
+		for _, item := range v {
+			found = append(found, stringsIn(item)...)
+		}
+	case map[string]any:
+		for _, item := range v {
+			found = append(found, stringsIn(item)...)
+		}
+	}
+
+	return found
+}
+
 // TestPagesCarryTheCSPNonce checks that every script and style block of each
 // page carries the nonce its Content-Security-Policy header names, so that the
 // browser runs and applies them, that each answer has a nonce of its own, and