Fix API Collection icon rendering in documentation

Adds the missing .collectionGroup case in renderKindAndRole function to ensure API Collections render as articles with collectionGroup role for correct icon display. Removes temporary test skip to enable validation of the fix.

rdar://135837611

Author: RalucaP

Sources/SwiftDocC/Model/Rendering/DocumentationContentRenderer.swift

@@ -264,6 +264,9 @@ public class DocumentationContentRenderer {
             return (.section, role)
         case .sampleCode:
             return (.article, role)
+
+        case .collectionGroup:
+            return (.article, role)
         case _ where kind.isSymbol:
             return (.symbol, role)
 

Tests/SwiftDocCTests/Rendering/DocumentationContentRendererTests.swift

@@ -133,11 +133,9 @@ class DocumentationContentRendererTests: XCTestCase {
     }
 
     func testRenderKindAndRoleForAPICollection() throws {
-        throw XCTSkip("TDD: Temporarily disabled while implementing API Collection icon fix")
-        
         // API Collections should render as articles with collectionGroup role to display correct icon
         let (collectionKind, collectionRole) = DocumentationContentRenderer.renderKindAndRole(.collectionGroup, semantic: nil)
-        XCTAssertEqual(collectionKind, RenderNode.Kind.article, "API Collections should render as articles, not symbols")
+        XCTAssertEqual(collectionKind, RenderNode.Kind.article, "API Collections should render as articles")
         XCTAssertEqual(collectionRole, "collectionGroup", "API Collections should have collectionGroup role for correct icon")
 
         // Verify other node types still work correctly