fix(docker): use host network mode for e2e mock server access

Both backend and frontend now use network_mode=host so the backend
can reach a mock HTTP server on the host's loopback interface during
e2e tests. VITE_BACKEND_URL env var set so frontend proxy reaches
host backend at localhost:8000.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

Docker/compose.debug.yml

@@ -73,8 +73,6 @@ services:
       - ../data/data:/data
       - fail2ban-dev-run:/var/run/fail2ban:ro
       - ../data/fail2ban-dev-config:/config:rw
-    ports:
-      - "${BANGUI_BACKEND_PORT:-8000}:8000"
     command:
       [
         "uvicorn", "app.main:create_app", "--factory",
@@ -87,8 +85,7 @@ services:
       timeout: 5s
       start_period: 45s
       retries: 5
-    networks:
-      - bangui-dev-net
+    network_mode: host
 
   # ── Frontend (Vite dev server with HMR) ─────────────────────
   frontend:
@@ -98,23 +95,15 @@ services:
     working_dir: /app
     environment:
       NODE_ENV: development
+      VITE_BACKEND_URL: "http://localhost:8000"
     volumes:
       - ../frontend:/app:z
       - frontend-node-modules:/app/node_modules
-    ports:
-      - "${BANGUI_FRONTEND_PORT:-5173}:5173"
     command: ["sh", "-c", "npm install && npm run dev -- --host 0.0.0.0"]
     depends_on:
       backend:
         condition: service_healthy
-    healthcheck:
-      test: ["CMD", "wget", "-qO", "/dev/null", "http://localhost:5173/"]
-      interval: 15s
-      timeout: 5s
-      start_period: 30s
-      retries: 5
-    networks:
-      - bangui-dev-net
+    network_mode: host
 
 volumes:
   bangui-dev-data: