feat(ss): support none/dummy cipher via no-op AEAD implementation

The go-gost fork of go-shadowsocks2 dropped built-in support for the
none/dummy cipher that was present in the original go-shadowsocks2.
Combined with the SS components' hard requirement for auth (and
therefore a valid cipher), this made gost fail to start with
method=none or method=dummy.

Add a no-op cipher in x/internal/util/ss/none/ that implements the
core.ShadowCipher interface using the standard go-shadowsocks2 AEAD
framing (salt + length-prefixed chunks, target address embedding)
without actual encryption.  SaltSize=16 ensures random salts on every
connection to avoid bloom-ring replay detection.

Update SS TCP connector/handler and SS UDP connector/handler to detect
method=none/dummy (case-insensitive) and use the no-op cipher instead
of utils.NewClientConfig/NewServerConfig.

Fixes go-gost/x#105

connector/ss/connector.go

@@ -7,6 +7,8 @@ import (
 	"net"
 	"time"
 
+	"strings"
+
 	"github.com/go-gost/core/common/bufpool"
 	"github.com/go-gost/core/connector"
 	md "github.com/go-gost/core/metadata"
@@ -15,6 +17,7 @@ import (
 	"github.com/go-gost/go-shadowsocks2/utils"
 	"github.com/go-gost/gosocks5"
 	ctxvalue "github.com/go-gost/x/ctx"
+	"github.com/go-gost/x/internal/util/ss/none"
 	"github.com/go-gost/x/registry"
 )
 
@@ -51,6 +54,11 @@ func (c *ssConnector) Init(md md.Metadata) (err error) {
 	method := c.options.Auth.Username()
 	password, _ := c.options.Auth.Password()
 
+	if strings.EqualFold(method, "none") || strings.EqualFold(method, "dummy") {
+		c.client = core.NewTCPClient(core.ClientConfig{Cipher: none.Cipher})
+		return
+	}
+
 	clientConfig, err := utils.NewClientConfig(method, password)
 	if err != nil {
 		return err

connector/ss/udp/connector.go

@@ -6,6 +6,7 @@ import (
 	"fmt"
 	"net"
 	"net/netip"
+	"strings"
 	"time"
 
 	"github.com/go-gost/core/connector"
@@ -16,6 +17,7 @@ import (
 	ctxvalue "github.com/go-gost/x/ctx"
 	"github.com/go-gost/x/internal/util/relay"
 	"github.com/go-gost/x/internal/util/ss"
+	ssnone "github.com/go-gost/x/internal/util/ss/none"
 	"github.com/go-gost/x/registry"
 )
 
@@ -52,6 +54,13 @@ func (c *ssuConnector) Init(md md.Metadata) (err error) {
 
 	method := c.options.Auth.Username()
 	password, _ := c.options.Auth.Password()
+
+	if strings.EqualFold(method, "none") || strings.EqualFold(method, "dummy") {
+		c.clientCfg = core.ClientConfig{Cipher: ssnone.Cipher, UDPTimeout: time.Minute}
+		c.tcpClient = core.NewTCPClient(core.ClientConfig{Cipher: ssnone.Cipher})
+		return
+	}
+
 	clientConfig, err := utils.NewClientConfig(method, password)
 	if err != nil {
 		return err