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

selective-vpn-api/app/httpx/helpers.go

@@ -0,0 +1,38 @@
+package httpx
+
+import (
+	"encoding/json"
+	"log"
+	"net/http"
+	"time"
+)
+
+func LogRequests(next http.Handler) http.Handler {
+	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		start := time.Now()
+		next.ServeHTTP(w, r)
+		log.Printf("%s %s %s", r.Method, r.URL.Path, time.Since(start))
+	})
+}
+
+func WriteJSON(w http.ResponseWriter, status int, v any) {
+	w.Header().Set("Content-Type", "application/json; charset=utf-8")
+	w.WriteHeader(status)
+	if v == nil {
+		return
+	}
+	if err := json.NewEncoder(w).Encode(v); err != nil {
+		log.Printf("writeJSON error: %v", err)
+	}
+}
+
+func HandleHealthz(w http.ResponseWriter, r *http.Request) {
+	if r.Method != http.MethodGet {
+		http.Error(w, "method not allowed", http.StatusMethodNotAllowed)
+		return
+	}
+	WriteJSON(w, http.StatusOK, map[string]string{
+		"status": "ok",
+		"time":   time.Now().Format(time.RFC3339),
+	})
+}