feat: build vehicle data platform and production pipeline

go/vehicle-gateway/internal/envelope/source.go

@@ -0,0 +1,19 @@
+package envelope
+
+import "strings"
+
+// NormalizeSourceEndpointKey returns the stable, low-cardinality source key used
+// by identity lookup and statistics source tracking.
+func NormalizeSourceEndpointKey(endpoint string) string {
+	endpoint = strings.TrimSpace(endpoint)
+	if endpoint == "" {
+		return ""
+	}
+	if strings.HasPrefix(strings.ToLower(endpoint), "mqtt://") {
+		return "mqtt"
+	}
+	if host, _, ok := strings.Cut(endpoint, ":"); ok {
+		return strings.TrimSpace(host)
+	}
+	return endpoint
+}