feat(agent): agent stream tunneling with TLS and dTLS (UDP); combined agent APIs

- Add `StreamPort` configuration to agent configuration and environment variables
- Implement TCP and UDP stream client support in agent package
- Update agent verification to test stream connectivity (TCP/UDP)
- Add `/info` endpoint to agent HTTP handler for version, name, runtime, and stream port
- Remove /version, /name, /runtime APIs, replaced by /info
- Update agent compose template to expose stream port for TCP and UDP
- Update agent creation API to optionally specify stream port (defaults to port + 1)
- Modify `StreamRoute` to pass agent configuration to stream implementations
- Update `TCPTCPStream` and `UDPUDPStream` to use agent stream tunneling when agent is configured
- Add support for both direct connections and agent-tunneled connections in stream routes

This enables agents to handle TCP and UDP route tunneling, expanding the proxy capabilities beyond HTTP-only connections.

agent/go.mod

@@ -18,6 +18,7 @@ require (
 	github.com/bytedance/sonic v1.14.2
 	github.com/gin-gonic/gin v1.11.0
 	github.com/gorilla/websocket v1.5.3
+	github.com/pion/dtls/v3 v3.0.9
 	github.com/puzpuzpuz/xsync/v4 v4.2.0
 	github.com/rs/zerolog v1.34.0
 	github.com/stretchr/testify v1.11.1
@@ -87,6 +88,8 @@ require (
 	github.com/opencontainers/image-spec v1.1.1 // indirect
 	github.com/oschwald/maxminddb-golang v1.13.1 // indirect
 	github.com/pelletier/go-toml/v2 v2.2.4 // indirect
+	github.com/pion/logging v0.2.4 // indirect
+	github.com/pion/transport/v3 v3.1.1 // indirect
 	github.com/pires/go-proxyproto v0.8.1 // indirect
 	github.com/pmezard/go-difflib v1.0.1-0.20181226105442-5d4384ee4fb2 // indirect
 	github.com/power-devops/perfstat v0.0.0-20240221224432-82ca36839d55 // indirect