fix: disable frontend service until Phase 4, simplify Caddy proxy

Frontend SvelteKit build has dependency conflicts (Svelte 5 + Vite 8).
Phase 0 setup wizard is served by FastAPI/Jinja2, no frontend needed.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

docker-compose.yml

@@ -51,13 +51,14 @@ services:
       - KORDOC_ENDPOINT=http://kordoc-service:3100
     restart: unless-stopped
 
-  frontend:
-    build: ./frontend
-    ports:
-      - "3000:3000"
-    depends_on:
-      - fastapi
-    restart: unless-stopped
+  # frontend: Phase 4에서 SvelteKit 빌드 안정화 후 활성화
+  # frontend:
+  #   build: ./frontend
+  #   ports:
+  #     - "3000:3000"
+  #   depends_on:
+  #     - fastapi
+  #   restart: unless-stopped
 
   caddy:
     image: caddy:2
@@ -69,7 +70,6 @@ services:
       - caddy_data:/data
     depends_on:
       - fastapi
-      - frontend
     restart: unless-stopped
 
 volumes: