Add staging elastic nav feature flag for edge environment (#1908)

* Initial plan

* Add staging elastic nav feature flag for edge environment

Co-authored-by: reakaleek <[email protected]>

* Remove FeatureFlagsTests.cs file as requested

Co-authored-by: reakaleek <[email protected]>

---------

Co-authored-by: copilot-swe-agent[bot] <[email protected]>
Co-authored-by: reakaleek <[email protected]>
Co-authored-by: Jan Calanog <[email protected]>

Author: Copilot

config/assembler.yml

@@ -30,6 +30,7 @@ environments:
     feature_flags:
       LAZY_LOAD_NAVIGATION: true
       SEARCH_OR_ASK_AI: true
+      STAGING_ELASTIC_NAV: true
   dev:
     uri: http://localhost:4000
     content_source: current

src/Elastic.Documentation.Configuration/Builder/FeatureFlags.cs

@@ -38,6 +38,12 @@ public bool SearchOrAskAiEnabled
 		set => _featureFlags["search-or-ask-ai"] = value;
 	}
 
+	public bool StagingElasticNavEnabled
+	{
+		get => IsEnabled("staging-elastic-nav");
+		set => _featureFlags["staging-elastic-nav"] = value;
+	}
+
 	private bool IsEnabled(string key)
 	{
 		var envKey = $"FEATURE_{key.ToUpperInvariant().Replace('-', '_')}";

src/Elastic.Documentation.Site/Layout/_Header.cshtml

@@ -3,7 +3,12 @@
 {
 	<div id="elastic-nav-wrapper">
 		<div id="elastic-nav" hx-disable="true"></div>
-		<script src="https://www.elastic.co/elastic-nav.js" async></script>
+		@{
+			var elasticNavUrl = Model.Features.StagingElasticNavEnabled 
+				? "https://stag-www.elastic.co/elastic-nav.js" 
+				: "https://www.elastic.co/elastic-nav.js";
+		}
+		<script src="@elasticNavUrl" async></script>
 	</div>
  	@await RenderPartialAsync(_SecondaryNav.Create(Model))
 }