WW-5640 Add WebJars support to Struts core (#1765)

* WW-5640 docs: design for WebJars support in Struts core

Adds first-class WebJars support so client-side libraries can be
referenced by a version-less logical path and served through the
existing static-content pipeline. Grounded against 7.2.x source.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

* WW-5640 docs: implementation plan for WebJars support

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

* WW-5640 build: add webjars-locator-lite dependency

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

* WW-5640 feat: add webjars config constants and defaults

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

* WW-5640 docs: correct plan test framework to JUnit 4

core uses JUnit 4 + AssertJ + Mockito, not JUnit 5 Jupiter (no
Jupiter engine on the classpath). Test tasks translate accordingly.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

* WW-5640 feat: add WebJarUrlProvider resolution seam

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

* WW-5640 feat: register WebJarUrlProvider bean

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

* WW-5640 feat: extend static content-type map for webjar assets

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

* WW-5640 feat: serve webjar assets via static content loader

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

* WW-5640 feat: add <s:webjar> tag and <@s.webjar> macro

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

* WW-5640 docs: add generated tag reference for <s:webjar>

Annotation-processor-generated tag reference (attributes + description),
tracked like every other tag's docs under core/src/site/resources/tags/.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

* WW-5640 fix: address final review (log level, resolveUrl traversal test, javadoc)

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

* WW-5640 refactor: address SonarCloud code smells

- getContentType: replace long if/else chain with a static extension->
  MIME map (S3776 cognitive complexity)
- DefaultWebJarUrlProvider.split: return Optional<String[]> instead of a
  null sentinel (S1168; Optional fits the reject semantics, empty-array
  would not)
- serving tests: rename local 'loader' -> 'webJarLoader' to stop hiding
  the ContentTypeProbe field (S1117)
- WebJarTest: use assertThat(writer).hasToString(...) (S5838)

S110 (WebJarTag inheritance depth) is inherent to the Struts tag base
class hierarchy shared by every tag; left as-is.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

---------

Co-authored-by: Claude Opus 4.8 <noreply@anthropic.com>

core/pom.xml

@@ -153,6 +153,17 @@
             <artifactId>caffeine</artifactId>
         </dependency>
 
+        <dependency>
+            <groupId>org.webjars</groupId>
+            <artifactId>webjars-locator-lite</artifactId>
+        </dependency>
+
+        <dependency>
+            <groupId>org.webjars</groupId>
+            <artifactId>jquery</artifactId>
+            <scope>test</scope>
+        </dependency>
+
         <dependency>
             <groupId>jakarta.servlet</groupId>
             <artifactId>jakarta.servlet-api</artifactId>