fix(thymeleaf): restore case-insensitive resolver matching in EngineFactory

The switch-expression refactor made the ClassLoader/Url arms case-
sensitive (exact match) while only the File arm kept equalsIgnoreCase —
the pre-refactor if/else matched all three case-insensitively. Restore
equalsIgnoreCase on all three arms so non-standard-cased property values
(e.g. fully-uppercase class names) behave identically to 1.0.x/2.0.x.
14 thymeleaf tests green.

Author: loong10k

easydoc-thymeleaf/src/main/java/io/github/easy4j/doc/thymeleaf/EngineFactory.java

@@ -62,10 +62,10 @@ public TemplateEngine get() throws IOException {
                     if (resolver == null) {
                         String resolverClassName = Docx4jProperties.getProperty("docx4j.thymeleaf.templateResolver", "org.thymeleaf.templateresolver.FileTemplateResolver");
                         // JDK 21 switch expression: 4-arm resolver selector becomes one expression.
-                        // Unknown values fall back to FileTemplateResolver, matching original else-branch.
+                        // All arms use equalsIgnoreCase to match the pre-refactor if/else behavior.
                         resolver = switch (resolverClassName) {
-                            case "org.thymeleaf.templateresolver.ClassLoaderTemplateResolver" -> new ClassLoaderTemplateResolver();
-                            case "org.thymeleaf.templateresolver.UrlTemplateResolver" -> new UrlTemplateResolver();
+                            case String s when s.equalsIgnoreCase("org.thymeleaf.templateresolver.ClassLoaderTemplateResolver") -> new ClassLoaderTemplateResolver();
+                            case String s when s.equalsIgnoreCase("org.thymeleaf.templateresolver.UrlTemplateResolver") -> new UrlTemplateResolver();
                             case String s when s.equalsIgnoreCase("org.thymeleaf.templateresolver.FileTemplateResolver") -> new FileTemplateResolver();
                             default -> new FileTemplateResolver();
                         };