feat(anthrax-cat): add Maneki-neko lucky cat decoration addon, remove easter egg

- New silverlabs:anthrax_cat entity: sitting cat with waving paw animation,
  idle body bob, look-at-player, fortune message + bell sound on interact
- Custom 64x64 texture (cream/white, red bib, gold coin, orange tabby patches)
- Custom geometry: body, head, ears, raised left arm, tail, bib, coin bones
- Removed easter egg addon mounts from all 4 servers (lobby + 3 child worlds)
- Anthrax Cat mounted on all 4 servers

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

addon/anthrax_cat_RP/entity/anthrax_cat.entity.json

@@ -0,0 +1,32 @@
+{
+  "format_version": "1.10.0",
+  "minecraft:client_entity": {
+    "description": {
+      "identifier": "silverlabs:anthrax_cat",
+      "materials": {
+        "default": "entity_alphatest"
+      },
+      "textures": {
+        "default": "textures/entity/anthrax_cat"
+      },
+      "geometry": {
+        "default": "geometry.anthrax_cat"
+      },
+      "render_controllers": [
+        "controller.render.anthrax_cat"
+      ],
+      "animations": {
+        "idle": "animation.anthrax_cat.idle",
+        "wave": "animation.anthrax_cat.wave",
+        "controller": "controller.animation.anthrax_cat"
+      },
+      "scripts": {
+        "animate": ["controller"]
+      },
+      "spawn_egg": {
+        "base_color": "#F5F5F0",
+        "overlay_color": "#CC1111"
+      }
+    }
+  }
+}