feat: implement MC domain filter proxy, API, dashboard

- proxy: asyncio TCP proxy with handshake parser, domain whitelist,
  transparent backend tunneling, SQLite logging, mtime hot reload
- api: FastAPI routes for config/domains/logs/status + restart trigger
- frontend: React + Vite NPM-style dashboard (dashboard/domains/logs/settings)
- nginx: reverse proxy for /api -> api:8000 and / -> frontend:3000
- docker-compose: full stack with shared data volume
- replace spec mc-domain-filter.md with README.md

frontend/vite.config.js

@@ -0,0 +1,19 @@
+import { defineConfig } from 'vite'
+import react from '@vitejs/plugin-react'
+
+// Dev 모드(localhost)에서는 /api 를 별도로 띄운 FastAPI 로 직접 프록시.
+// Docker 환경에서는 nginx 컨테이너가 /api 와 / 를 모두 한 host 에서 라우팅한다.
+export default defineConfig({
+  plugins: [react()],
+  server: {
+    host: '0.0.0.0',
+    port: 3000,
+    proxy: {
+      '/api': 'http://localhost:8000',
+    },
+  },
+  preview: {
+    host: '0.0.0.0',
+    port: 3000,
+  },
+})