Cache: fix 1-year CSS cache and add version busting

- .htaccess: remove duplicate cache block that set all CSS/JS to max-age=31536000
  CSS/JS now use max-age=3600 must-revalidate (was 1 year, breaking live edits)
- index.php: bump main.min.css version v1.1.3 -> v1.1.4
- All 78 PHP files: add ?v=20260222 to main.css and cro-enhancements.css refs
  Forces browser cache bust for all pages after todays accessibility changes

privacy-policy.php

@@ -38,7 +38,7 @@ $canonical_url = "https://ukdataservices.co.uk/privacy-policy";
     <link rel="preconnect" href="https://fonts.googleapis.com">
     <link rel="preconnect" href="https://fonts.gstatic.com" crossorigin>
     <link href="https://fonts.googleapis.com/css2?family=Roboto+Slab:ital,wght@0,100;0,200;0,300;0,400;0,500;0,600;0,700;0,800;0,900;1,100;1,200;1,300;1,400;1,500;1,600;1,700;1,800;1,900&family=Lato:ital,wght@0,100;0,200;0,300;0,400;0,500;0,600;0,700;0,800;0,900;1,100;1,200;1,300;1,400;1,500;1,600;1,700;1,800;1,900&display=swap" rel="stylesheet">
-    <link rel="stylesheet" href="assets/css/main.css">
+    <link rel="stylesheet" href="assets/css/main.css?v=20260222">
     
     <style>
         .legal-content {