feat: initialize warpbox.dev project structure and backend

Initialize the repository with the core Go backend architecture and a frontend mockup for warpbox.dev, a self-hosted file-sharing application.

- Set up Go backend modules for configuration, HTTP server, middleware, handlers, and templates.
- Add local development scripts, environment templates, and basic project configuration.
- Include a React-based frontend mockup under the docs directory.

backend/libs/middleware/request_id.go

@@ -0,0 +1,38 @@
+package middleware
+
+import (
+	"context"
+	"crypto/rand"
+	"encoding/hex"
+	"net/http"
+)
+
+type requestIDKey struct{}
+
+func RequestID(next http.Handler) http.Handler {
+	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		requestID := r.Header.Get("X-Request-ID")
+		if requestID == "" {
+			requestID = newRequestID()
+		}
+
+		w.Header().Set("X-Request-ID", requestID)
+		ctx := context.WithValue(r.Context(), requestIDKey{}, requestID)
+		next.ServeHTTP(w, r.WithContext(ctx))
+	})
+}
+
+func RequestIDFromContext(ctx context.Context) string {
+	if value, ok := ctx.Value(requestIDKey{}).(string); ok {
+		return value
+	}
+	return ""
+}
+
+func newRequestID() string {
+	var data [16]byte
+	if _, err := rand.Read(data[:]); err != nil {
+		return "request-id-unavailable"
+	}
+	return hex.EncodeToString(data[:])
+}