further bug fixes when using context path (#1475)

Co-authored-by: Anthony Stirling <77850077+Frooodle@users.noreply.github.com>

src/main/resources/templates/convert/pdf-to-html.html

@@ -17,7 +17,7 @@
                 <span class="material-symbols-rounded tool-header-icon convert">html</span>
                 <span class="tool-header-text" th:text="#{PDFToHTML.header}"></span>
               </div>
-              <form method="post" enctype="multipart/form-data" th:action="@{api/v1/convert/pdf/html}">
+              <form method="post" enctype="multipart/form-data" th:action="@{'/api/v1/convert/pdf/html'}">
                 <div th:replace="~{fragments/common :: fileSelector(name='fileInput', multiple=false, accept='application/pdf')}"></div>
                 <br>
                 <button type="submit" id="submitBtn" class="btn btn-primary" th:text="#{PDFToHTML.submit}"></button>