Add thymeleaf-htmx module: Spring Boot 4.1.2 + Thymeleaf 3.1.5 + htmx 2.0.11 CRUD UI with fragment rendering, 422 validation re-render, pagination, inline edit, delete, MockMvc tests and a Chromium check

Co-Authored-By: Claude Sonnet 5.5 <[email protected]>
Claude-Session: https://claude.ai/code/session_017ic4b7rnC7jppGGdHGESvy

thymeleaf-htmx/src/main/resources/templates/layout/base.html

@@ -0,0 +1,18 @@
+<!DOCTYPE html>
+<html lang="en" xmlns:th="http://www.thymeleaf.org"
+      th:fragment="layout(title, content)">
+<head>
+  <meta charset="utf-8">
+  <meta name="viewport" content="width=device-width, initial-scale=1">
+  <title th:replace="${title}">Contacts</title>
+  <!-- htmx 2 swaps 2xx/3xx only. 422 must be allowed to swap, or validation errors never appear. -->
+  <meta name="htmx-config"
+        content='{"responseHandling":[{"code":"204","swap":false},{"code":"[23]..","swap":true},{"code":"422","swap":true,"error":false},{"code":"[45]..","swap":false,"error":true},{"code":"...","swap":false}]}'>
+  <link rel="stylesheet" th:href="@{/css/app.css}">
+  <script th:src="@{/webjars/htmx.org/dist/htmx.min.js}" defer></script>
+</head>
+<body>
+  <header><a th:href="@{/contacts}">Contacts</a></header>
+  <main th:replace="${content}">page content goes here</main>
+</body>
+</html>