feat: support self-host docker build (#5506)

Test command: `docker compose -f ./.github/deployment/self-host/compose.yaml up`

packages/backend/server/package.json

@@ -32,6 +32,7 @@
     "@nestjs/platform-express": "^10.2.10",
     "@nestjs/platform-socket.io": "^10.2.10",
     "@nestjs/schedule": "^4.0.0",
+    "@nestjs/serve-static": "^4.0.0",
     "@nestjs/throttler": "^5.0.1",
     "@nestjs/websockets": "^10.2.10",
     "@node-rs/argon2": "^1.5.2",
@@ -57,6 +58,7 @@
     "@socket.io/redis-adapter": "^8.2.1",
     "cookie-parser": "^1.4.6",
     "dotenv": "^16.3.1",
+    "dotenv-cli": "^7.3.0",
     "express": "^4.18.2",
     "file-type": "^19.0.0",
     "get-stream": "^8.0.1",