feat: enhance accessibility and testing with data-test attributes and improve error handling

apps/web/i18n/messages/en/siteBuilder.json

@@ -0,0 +1,53 @@
+{
+  "nav": {
+    "pages": "Pages",
+    "posts": "Posts",
+    "settings": "Settings"
+  },
+  "pages": {
+    "title": "Pages",
+    "newPage": "New Page",
+    "noPages": "No pages found",
+    "createFirst": "Create your first page.",
+    "pageTitle": "Page Title *",
+    "slug": "URL Path",
+    "slugPlaceholder": "Leave empty for auto-generation...",
+    "membersOnly": "Members Only",
+    "createAndEdit": "Create Page & Open Editor",
+    "pageCreated": "Page created — opening editor",
+    "errorCreating": "Error creating page",
+    "notFound": "Page not found",
+    "published": "Page published",
+    "error": "Error"
+  },
+  "posts": {
+    "title": "Posts",
+    "newPost": "New Post",
+    "noPosts": "No posts found",
+    "createFirst": "Create your first post.",
+    "postTitle": "Title *",
+    "content": "Post content (HTML allowed)...",
+    "excerpt": "Excerpt",
+    "postCreated": "Post created",
+    "errorCreating": "Error"
+  },
+  "settings": {
+    "title": "Settings",
+    "saved": "Settings saved",
+    "error": "Error"
+  },
+  "editor": {
+    "publish": "Publish",
+    "unpublish": "Unpublish"
+  },
+  "portal": {
+    "loginSuccess": "Logged in successfully",
+    "membersArea": "Members Area"
+  },
+  "blocks": {
+    "news": "News",
+    "events": "Events",
+    "loginError": "Login error",
+    "connectionError": "Connection error"
+  }
+}