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/subscribe/subscribeLogic.go

@@ -101,6 +101,11 @@ func (l *SubscribeLogic) Handler(req *types.SubscribeRequest) (resp *types.Subsc
 	if err != nil {
 		return nil, err
 	}
+	// Experimental protocols (simnet) are only delivered to their own clients/SDK
+	// (UA hits omnxt/slag/slaglab). Hide them from every other client so a
+	// generic template never renders a broken/unusable node. Mirrors the Pro
+	// reference FilterExperimentalNodesForClient.
+	servers = filterExperimentalNodesForClient(servers, userAgent)
 	a := adapter.NewAdapter(
 		targetApp.SubscribeTemplate,
 		adapter.WithServers(servers),
@@ -109,6 +114,7 @@ func (l *SubscribeLogic) Handler(req *types.SubscribeRequest) (resp *types.Subsc
 		adapter.WithOutputFormat(targetApp.OutputFormat),
 		adapter.WithUserInfo(adapter.User{
 			Password:     userSubscribe.UUID,
+			SubscribeID:  userSubscribe.Id,
 			ExpiredAt:    userSubscribe.ExpireTime,
 			Download:     userSubscribe.Download,
 			Upload:       userSubscribe.Upload,