platform: modularize api/gui, add docs-tests-web foundation, and refresh root config

selective-vpn-api/app/transport_handlers_runtime_observability.go

@@ -0,0 +1,14 @@
+package app
+
+import (
+	"net/http"
+	"time"
+)
+
+func handleTransportRuntimeObservability(w http.ResponseWriter, r *http.Request) {
+	if r.Method != http.MethodGet {
+		http.Error(w, "method not allowed", http.StatusMethodNotAllowed)
+		return
+	}
+	writeJSON(w, http.StatusOK, transportRuntimeObservabilitySnapshotResponse(time.Now().UTC()))
+}