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.

config.example.yaml

@@ -2,6 +2,9 @@
 #
 # Semantics: client calls  GET /api/{alias}/health
 #            forwarded to   GET {base_url}/v1/health
+#
+# Web UI (SvelteKit) в образе Docker встроен в тот же процесс: GET / — панель,
+# /api/… — API. CORS для панели на том же origin не нужен.
 
 listen: ":8080"
 
@@ -23,7 +26,8 @@ whitelist_cidrs:
 #   - "10.0.0.0/8"
 trusted_proxies: []
 
-# SPA на другом origin (preflight OPTIONS + Access-Control-Allow-Origin):
+# CORS только если фронт на другом origin (например Vite :5173 при разработке).
+# В production за nginx на одном хосте с шлюзом обычно не требуется.
 # cors_allowed_origins:
 #   - "http://localhost:5173"
 #   # - "*"