✨ feat(page-chat): add markdown rendering, message editing, and conte…

…xt menu

- Integrate `marked` and `unsafeHTML` for markdown rendering in AI messages
- Introduce unique message IDs for tracking and editing
- Implement message editing, copying, and resending functionality via context menu
- Display AI typing indicator and add scroll-to-bottom button
- Enhance layout and styling for mobile responsiveness
- Store and retrieve chat history in localStorage

.gitignore

@@ -4,3 +4,4 @@ diff.txt
 .devcontainer/
 .github/
 .vscode/
+*.pub

package.json

@@ -25,8 +25,13 @@
   "dependencies": {
     "@lit-labs/signals": "^0.1.1",
     "@lit/context": "^1.1.3",
+    "@types/dompurify": "^3.0.5",
     "@vaadin/router": "^2.0.0",
+    "dompurify": "^3.2.3",
+    "highlight.js": "^11.11.1",
     "lit": "^2.7.1",
+    "marked": "^15.0.6",
+    "marked-highlight": "^2.2.1",
     "pwa-helper-components": "~0.2.10",
     "tslib": "^2.5.0"
   },