feat(furnieditor): split-aware FurniDataManager + JSON5 tolerance

Aligns the :furnidata in-game admin command with the split-aware gamedata
layout shipped by the Nitro V3 client. FurniDataManager now resolves the
furnidata source through three accepted shapes:

- legacy single-file path (filesystem or http URL ending in .json/.json5)
- split-mode directory (URL ending with '/') — walks core/custom/seasonal
  tiers via manifest.json5 files and merges by item id, with later tiers
  overriding earlier ones (same semantics as the client-side loader)
- fallback to furni.editor.asset.base.path when the renderer config is
  missing or contains an unresolved placeholder

Adds a small JSON5 sanitiser (stripJson5) that removes line and block
comments and trailing commas before handing the content to Gson, so both
the renderer config and the split-mode files can be JSON or JSON5
without pulling in a JSON5 dependency. String contents are preserved
verbatim — comment-looking substrings inside strings (e.g. URLs) are
not touched.

Bumps the emulator version to 4.2.6.

Emulator/pom.xml

@@ -6,7 +6,7 @@
 
     <groupId>com.eu.habbo</groupId>
     <artifactId>Habbo</artifactId>
-    <version>4.1.16</version>
+    <version>4.2.6</version>
 
     <properties>
         <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>