Improve source file detection and tests

- Use SwiftPM-provided sourceFiles for filtering - Add Utils.swift with
URL descendant check - Update example to use Views/ instead of Folder/ -
Add test for non-included Swift file - Update .zed settings to disable
VSCode CSS language server

Plugins/TailwindCSS/Utils.swift

@@ -0,0 +1,24 @@
+import Foundation
+
+extension URL {
+  func isOrIsDescendant(of ancestor: URL) -> Bool {
+    guard ancestor.isFileURL, self.isFileURL else {
+      return false
+    }
+
+    let ancestorComponents = ancestor.pathComponents
+    let selfComponents = self.pathComponents
+
+    guard selfComponents.count >= ancestorComponents.count else {
+      return false
+    }
+
+    for (index, component) in ancestorComponents.enumerated() {
+      if selfComponents[index] != component {
+        return false
+      }
+    }
+
+    return true
+  }
+}