DEV: Merge topic list card component (#17)

This PR merges the topic-list-item card component into the nextgen theme.

Also does the following cleanup:

* Use template-only ember components
* Use `fire` instead of deprecated `fa-fire` icon
* Lower version requirement for node to 18 to match core
* Add english locale strings for topic status column
* Remove dummy theme settings

---------

Co-authored-by: Martin Brennan <martin@discourse.org>

package.json

@@ -7,7 +7,7 @@
     "prettier": "2.8.8"
   },
   "engines": {
-    "node": ">= 22",
+    "node": ">= 18",
     "npm": "please-use-pnpm",
     "yarn": "please-use-pnpm",
     "pnpm": "9.x"