revert(stack): un-merge docker-dev-sync, restore as independent B-route directory

docker-dev 清理合并残留：去掉 rsync/mkdir/chmod、删 ulthon_admin_sync 服务、
删 .env(COMPOSE_PROFILES)、删 sync.sh、删 .dockerignore、去 SYNC_INTERVAL。
docker-dev-sync 恢复独立目录并 B-route 化（context: ../../..）。
两个模式各自独立、各自完整。

source/stack/docker-dev/docker-compose.yaml

@@ -52,24 +52,3 @@ services:
         depends_on:
             mysql:
                 condition: service_healthy
-
-    # Sync profile: Windows I/O optimization via rsync host->container
-    # Enable with: COMPOSE_PROFILES=sync docker compose up -d
-    # Note: ulthon_admin and ulthon_admin_sync both bind port 8000, do not run together.
-    ulthon_admin_sync:
-        profiles: ["sync"]
-        build:
-            context: ../../..
-            dockerfile: source/stack/docker-dev/Dockerfile
-        restart: unless-stopped
-        ports:
-            - "8000:8000"
-        volumes:
-            - ../../..:/var/www/source
-        environment:
-            - SYNC_INTERVAL=${SYNC_INTERVAL:-3}
-        extra_hosts:
-            - "host.docker.internal:host-gateway"
-        depends_on:
-            mysql:
-                condition: service_healthy