Add demo mTLS client certificates and key

Included at the repository owner's request for demonstration and
integration testing only. Revocable on the robot side; not for
production use.

certs/client_tls.conf

@@ -0,0 +1,26 @@
+# Android 客户端 TLS/DTLS 加密通信配置文件
+
+[global]
+role = "client"
+verify_peer = true
+security_level = 1
+hw_accel = false
+secure_memory = false
+
+[certificates]
+# 文件身份模式必须显式声明 source="file" + allow_file_identity=true
+# Android 默认身份源为 android_keystore，文件私钥模式需强制开启
+source = "file"
+allow_file_identity = true
+# 运行时路径由 App 在代码中动态设置（从 assets 复制到 filesDir/certs/）
+cert_file = client_chain.crt
+key_file = client.key
+ca_file = root_ca.crt
+
+[tcp]
+keepalive_interval = 30
+nodelay = true
+
+[udp]
+mtu = 1500
+cookie_verify = true