fix(matcher,plugin): case-insensitive matching, port accumulation, nil guards, doc comments

matcher: fix IPv6 normalization via netip.ParseAddr, port-range overwrite
by switching to []*PortRange map, case-insensitive domain/host matching,
glob.MustCompile→Compile to avoid panic on invalid patterns.

plugin: guard nil *Options in NewGRPCConn and NewHTTPClient; add
HTTPClientTransport helper for idle-connection cleanup.

net/*: add doc comments for all exported symbols (no code changes).

Add 30 tests (matcher_test.go 22, plugin_test.go 8) covering all
matcher types, nil safety, case insensitivity, IPv6 normalization,
port ranges, and plugin option composition.

internal/net/udp/conn.go

@@ -7,6 +7,8 @@ import (
 	xnet "github.com/go-gost/x/internal/net"
 )
 
+// Conn is a net.PacketConn that also supports io.Reader, io.Writer, buffer
+// sizing, syscall access, and remote address exposure.
 type Conn interface {
 	net.PacketConn
 	io.Reader
@@ -18,11 +20,13 @@ type Conn interface {
 	xnet.RemoteAddr
 }
 
+// ReadUDP supports reading UDP datagrams with metadata.
 type ReadUDP interface {
 	ReadFromUDP(b []byte) (n int, addr *net.UDPAddr, err error)
 	ReadMsgUDP(b, oob []byte) (n, oobn, flags int, addr *net.UDPAddr, err error)
 }
 
+// WriteUDP supports writing UDP datagrams with metadata.
 type WriteUDP interface {
 	WriteToUDP(b []byte, addr *net.UDPAddr) (int, error)
 	WriteMsgUDP(b, oob []byte, addr *net.UDPAddr) (n, oobn int, err error)

internal/net/udp/listener.go

@@ -11,6 +11,7 @@ import (
 	"github.com/go-gost/core/logger"
 )
 
+// ListenConfig configures a UDP-to-TCP-stream listener.
 type ListenConfig struct {
 	Addr           net.Addr
 	Backlog        int
@@ -29,6 +30,9 @@ type listener struct {
 	config   *ListenConfig
 }
 
+// NewListener creates a net.Listener from a net.PacketConn by demultiplexing
+// UDP datagrams into per-client net.Conn streams. Idle connections are cleaned
+// up according to cfg.TTL.
 func NewListener(conn net.PacketConn, cfg *ListenConfig) net.Listener {
 	if cfg == nil {
 		cfg = &ListenConfig{}

internal/net/udp/relay.go

@@ -13,6 +13,7 @@ const (
 	defaultBufferSize = 4096
 )
 
+// Relay copies UDP datagrams between two net.PacketConns bidirectionally.
 type Relay struct {
 	service    string
 	pc1        net.PacketConn
@@ -22,6 +23,7 @@ type Relay struct {
 	logger     logger.Logger
 }
 
+// NewRelay creates a Relay that copies datagrams between pc1 and pc2.
 func NewRelay(pc1, pc2 net.PacketConn) *Relay {
 	return &Relay{
 		pc1: pc1,
@@ -29,26 +31,31 @@ func NewRelay(pc1, pc2 net.PacketConn) *Relay {
 	}
 }
 
+// WithService sets the service name for bypass matching.
 func (r *Relay) WithService(service string) *Relay {
 	r.service = service
 	return r
 }
 
+// WithBypass sets the bypass matcher to skip certain addresses.
 func (r *Relay) WithBypass(bp bypass.Bypass) *Relay {
 	r.bypass = bp
 	return r
 }
 
+// WithLogger sets the logger.
 func (r *Relay) WithLogger(logger logger.Logger) *Relay {
 	r.logger = logger
 	return r
 }
 
+// WithBufferSize sets the buffer size for copy operations.
 func (r *Relay) WithBufferSize(n int) *Relay {
 	r.bufferSize = n
 	return r
 }
 
+// Run starts the relay. It blocks until an error occurs or ctx is cancelled.
 func (r *Relay) Run(ctx context.Context) (err error) {
 	errc := make(chan error, 2)