Add local-first race hub API

internal/web/source.go

@@ -0,0 +1,24 @@
+package web
+
+import "net/http"
+
+const (
+	sourceOpenF1 = "openf1"
+	sourceLocal  = "local"
+	sourceAuto   = "auto"
+)
+
+func parseSourceMode(r *http.Request) string {
+	switch r.URL.Query().Get("source") {
+	case sourceLocal:
+		return sourceLocal
+	case sourceAuto:
+		return sourceAuto
+	default:
+		return sourceOpenF1
+	}
+}
+
+func (s *Server) hasLocalQuery() bool {
+	return s.query != nil
+}