refactor: Remove unused stripHTMLSimple method from StringExtensions

- Remove stripHTMLSimple regex-based HTML stripping method
- Keep stripHTML with NSAttributedString-based implementation (used in codebase)
- Method was not used anywhere in the project

readeck/UI/Utils/StringExtensions.swift

@@ -13,17 +13,5 @@ extension String {
         )
         
         return attributedString?.string ?? self
-    }
-    
-    var stripHTMLSimple: String {
-        // Einfache Regex-basierte HTML-Entfernung
-        return self.replacingOccurrences(of: "<[^>]+>", with: "", options: .regularExpression, range: nil)
-            .replacingOccurrences(of: "&nbsp;", with: " ")
-            .replacingOccurrences(of: "&amp;", with: "&")
-            .replacingOccurrences(of: "&lt;", with: "<")
-            .replacingOccurrences(of: "&gt;", with: ">")
-            .replacingOccurrences(of: "&quot;", with: "\"")
-            .replacingOccurrences(of: "&#39;", with: "'")
-            .trimmingCharacters(in: .whitespacesAndNewlines)
-    }
-} 
+    }   
+}