[management] Add dashboard_features account setting for per-section visibility

Introduce a nullable dashboard_features object on account settings, serialized
to a single JSON column so new dashboard sections can be added without schema
changes. Starts with agent_network (show the Agent Network menu for an account
without the deployment flag). Wires the API handler mapping, the pgx GetAccount
loader, and adds store round-trip and handler tests.

management/server/http/handlers/accounts/accounts_handler.go

@@ -289,6 +289,11 @@ func (h *handler) updateAccountRequestSettings(req api.PutApiAccountsAccountIdJS
 	if req.Settings.AgentNetworkOnly != nil {
 		returnSettings.AgentNetworkOnly = *req.Settings.AgentNetworkOnly
 	}
+	if req.Settings.DashboardFeatures != nil {
+		returnSettings.DashboardFeatures = &types.DashboardFeatures{
+			AgentNetwork: req.Settings.DashboardFeatures.AgentNetwork,
+		}
+	}
 
 	return returnSettings, nil
 }
@@ -434,6 +439,11 @@ func toAccountResponse(accountID string, settings *types.Settings, meta *types.A
 		networkRangeV6Str := settings.NetworkRangeV6.String()
 		apiSettings.NetworkRangeV6 = &networkRangeV6Str
 	}
+	if settings.DashboardFeatures != nil {
+		apiSettings.DashboardFeatures = &api.AccountDashboardFeatures{
+			AgentNetwork: settings.DashboardFeatures.AgentNetwork,
+		}
+	}
 
 	apiOnboarding := api.AccountOnboarding{
 		OnboardingFlowPending: onboarding.OnboardingFlowPending,

management/server/http/handlers/accounts/accounts_handler_test.go

@@ -312,6 +312,38 @@ func TestAccounts_AccountsHandler(t *testing.T) {
 			expectedArray: false,
 			expectedID:    accountID,
 		},
+		{
+			name:           "PutAccount OK setting dashboard_features agent_network",
+			expectedBody:   true,
+			requestType:    http.MethodPut,
+			requestPath:    "/api/accounts/" + accountID,
+			requestBody:    bytes.NewBufferString("{\"settings\": {\"peer_login_expiration\": 15552000,\"peer_login_expiration_enabled\": true,\"dashboard_features\": {\"agent_network\": true}},\"onboarding\": {\"onboarding_flow_pending\": true,\"signup_form_pending\": true}}"),
+			expectedStatus: http.StatusOK,
+			expectedSettings: api.AccountSettings{
+				PeerLoginExpiration:             15552000,
+				PeerLoginExpirationEnabled:      true,
+				GroupsPropagationEnabled:        br(false),
+				JwtGroupsClaimName:              sr(""),
+				JwtGroupsEnabled:                br(false),
+				JwtAllowGroups:                  &[]string{},
+				RegularUsersViewBlocked:         false,
+				RoutingPeerDnsResolutionEnabled: br(false),
+				LazyConnectionEnabled:           br(false),
+				DnsDomain:                       sr(""),
+				AutoUpdateAlways:                br(false),
+				AutoUpdateVersion:               sr(""),
+				MetricsPushEnabled:              br(false),
+				AgentNetworkOnly:                br(false),
+				DashboardFeatures: &api.AccountDashboardFeatures{
+					AgentNetwork: br(true),
+				},
+				EmbeddedIdpEnabled: br(false),
+				LocalAuthDisabled:  br(false),
+				LocalMfaEnabled:    br(false),
+			},
+			expectedArray: false,
+			expectedID:    accountID,
+		},
 		{
 			name:           "PutAccount OK disabling agent_network_only again",
 			expectedBody:   true,