Add Docker daemon and service hardening configurations

- config/docker/daemon.json: Docker security hardening with logging limits and security options
- config/systemd/nginx.service.d/rate-limit.conf: Nginx resource limits and connection throttling
- Includes deployment instructions for container and service security

config/docker/daemon.json

@@ -0,0 +1,32 @@
+# Docker Daemon Security Configuration
+# Deploy to: /etc/docker/daemon.json
+# 
+# Setup commands:
+#   sudo cp config/docker/daemon.json /etc/docker/
+#   sudo systemctl restart docker
+
+{
+  "log-driver": "json-file",
+  "log-opts": {
+    "max-size": "50m",
+    "max-file": "3"
+  },
+  "live-restore": true,
+  "userland-proxy": false,
+  "no-new-privileges": true,
+  "seccomp-profile": "/etc/docker/seccomp-default.json",
+  "default-ulimits": {
+    "nproc": {
+      "hard": 65536,
+      "soft": 65536
+    },
+    "nofile": {
+      "hard": 65536,
+      "soft": 65536
+    }
+  },
+  "storage-driver": "overlay2",
+  "storage-opts": [
+    "overlay2.override_kernel_check=true"
+  ]
+}