chore: delete ecs-browser package

.changeset/khaki-doors-refuse.md

@@ -0,0 +1,5 @@
+---
+"@latticexyz/ecs-browser": major
+---
+
+Removes `ecs-browser` package. This has now been replaced by `dev-tools`, which comes out-of-the-box when creating a new MUD app from the templates (`pnpm create mud@next your-app-name`). We'll be adding deeper RECS support (querying for entities) in a future release.