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/pkg/agent/stream/common.go

@@ -0,0 +1,57 @@
+package stream
+
+import (
+	"net"
+	"time"
+
+	"github.com/puzpuzpuz/xsync/v4"
+	"github.com/yusing/goutils/synk"
+)
+
+const (
+	dialTimeout  = 10 * time.Second
+	readDeadline = 10 * time.Second
+)
+
+var sizedPool = synk.GetSizedBytesPool()
+
+type CreateConnFunc[Conn net.Conn] func(host, port string) (Conn, error)
+type ConnectionManager[Conn net.Conn] struct {
+	m                *xsync.Map[string, Conn]
+	createConnection CreateConnFunc[Conn]
+}
+
+func NewConnectionManager[Conn net.Conn](createConnection CreateConnFunc[Conn]) *ConnectionManager[Conn] {
+	return &ConnectionManager[Conn]{
+		m:                xsync.NewMap[string, Conn](),
+		createConnection: createConnection,
+	}
+}
+
+func (c *ConnectionManager[Conn]) GetOrCreateDestConnection(clientConn net.Conn, host, port string) (ret Conn, connErr error) {
+	clientKey := clientConn.RemoteAddr().String()
+	ret, _ = c.m.LoadOrCompute(clientKey, func() (conn Conn, cancel bool) {
+		conn, connErr = c.createConnection(host, port)
+		if connErr != nil {
+			cancel = true
+		}
+		return
+	})
+
+	return
+}
+
+func (c *ConnectionManager[Conn]) DeleteDestConnection(clientConn net.Conn) {
+	clientKey := clientConn.RemoteAddr().String()
+	conn, loaded := c.m.LoadAndDelete(clientKey)
+	if loaded {
+		conn.Close()
+	}
+}
+
+func (c *ConnectionManager[Conn]) CloseAllConnections() {
+	for _, conn := range c.m.Range {
+		conn.Close()
+	}
+	c.m.Clear()
+}