feat(simnet): add SimNet protocol end-to-end support

- model: SimNet protocol fields + NormalizeSimnet; type+port protocol uniqueness
- server config: OmnXT runtime config delivery via compatible() simnet case
- credentials: derive per-user psk/key_id from subscription (pkg/simnet), no new table
- subscription: adapter buildOmnxtSimnetConfigs + base64 buildOmnxtProtocolLinks + OmnXT SimNet application (migration 02161)
- UA gating: hide experimental protocols from non first-party clients (download + JSON node-list)
- admin: normalize simnet on create/update and on GET responses
- tests: 21 simnet unit tests; full suite green

internal/logic/server/constant.go

@@ -12,6 +12,7 @@ const (
 	// Deprecated: Hysteria2 is deprecated, use Hysteria instead
 	// TODO: remove in future versions
 	Hysteria2 = "hysteria2"
+	Simnet    = "simnet"
 )
 
 type SecurityConfig struct {

internal/logic/server/getServerConfigLogic.go

@@ -234,6 +234,22 @@ func (l *GetServerConfigLogic) compatible(config node.Protocol) map[string]inter
 			},
 		}
 
+	case Simnet:
+		// Simnet ships its whole normalized protocol as the node runtime config
+		// (server PSK key_id=0, path, carrier, TLS, AF, fallback, reverse, resource
+		// limits), matching the Pro reference (compat_legacy.go simnet case).
+		config.NormalizeSimnet()
+		// Config snapshot log — non-sensitive fields only (never log the PSK).
+		l.Infow("[GetServerConfig] simnet runtime config",
+			logger.Field("port", config.Port),
+			logger.Field("path", config.SimnetPath),
+			logger.Field("carrier", config.SimnetCarrier),
+			logger.Field("security", config.Security),
+			logger.Field("af_enabled", config.SimnetAfEnabled),
+			logger.Field("fallback_enabled", config.SimnetFallbackEnabled),
+		)
+		result = config
+
 	}
 	var resp map[string]interface{}
 	s, _ := json.Marshal(result)

internal/logic/server/getServerUserListLogic_test.go

@@ -38,6 +38,7 @@ func TestNormalizeServerUserListProtocol(t *testing.T) {
 		{"tuic unchanged", "tuic", "tuic"},
 		{"shadowsocks unchanged", "shadowsocks", "shadowsocks"},
 		{"anytls unchanged", "anytls", "anytls"},
+		{"simnet unchanged", "simnet", "simnet"},
 		{"empty unchanged", "", ""},
 	}
 	for _, c := range cases {