Refactor Docker setup to integrate Web UI and streamline configuration

- Updated Dockerfile to build and embed the SvelteKit Web UI directly into the gateway image, eliminating the need for a separate web service.
- Modified .dockerignore to exclude unnecessary directories related to the web service.
- Adjusted config.compose.yaml to remove CORS settings for the web service, as the UI now shares the same origin as the API.
- Enhanced README.md to reflect the new single-port architecture for accessing both the Web UI and API.
- Removed the standalone web Dockerfile and updated related documentation for local development and build processes.

internal/webui/handler.go

@@ -0,0 +1,68 @@
+package webui
+
+import (
+	"io/fs"
+	"mime"
+	"net/http"
+	"path"
+	"strconv"
+	"strings"
+)
+
+// Handler отдаёт статику SvelteKit (embed) и index.html для клиентских маршрутов SPA.
+func Handler() http.Handler {
+	root, err := fs.Sub(static, "static")
+	if err != nil {
+		return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+			http.NotFound(w, r)
+		})
+	}
+
+	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		if r.Method != http.MethodGet && r.Method != http.MethodHead {
+			http.Error(w, "method not allowed", http.StatusMethodNotAllowed)
+			return
+		}
+
+		name := strings.TrimPrefix(path.Clean(r.URL.Path), "/")
+		if name == "." || name == "" {
+			name = "index.html"
+		}
+
+		b, err := fs.ReadFile(root, name)
+		if err != nil {
+			if path.Ext(name) != "" {
+				http.NotFound(w, r)
+				return
+			}
+			b, err = fs.ReadFile(root, "index.html")
+			if err != nil {
+				http.NotFound(w, r)
+				return
+			}
+			name = "index.html"
+		}
+
+		ct := mime.TypeByExtension(path.Ext(name))
+		if ct == "" {
+			ct = "application/octet-stream"
+		}
+		if strings.HasPrefix(ct, "text/") && !strings.Contains(ct, "charset") {
+			ct = ct + "; charset=utf-8"
+		}
+		w.Header().Set("Content-Type", ct)
+		if name == "index.html" {
+			w.Header().Set("Cache-Control", "no-cache")
+		} else {
+			w.Header().Set("Cache-Control", "public, max-age=31536000, immutable")
+		}
+
+		if r.Method == http.MethodHead {
+			w.Header().Set("Content-Length", strconv.Itoa(len(b)))
+			w.WriteHeader(http.StatusOK)
+			return
+		}
+		w.WriteHeader(http.StatusOK)
+		_, _ = w.Write(b)
+	})
+}