Add creator field and enriched tooltip for data-driven items

- Add optional "creator" JSON field to display author name in tooltip
- Show body regions, movement style, lock status, and escape difficulty
- Show pose priority and item ID in advanced mode (F3+H)
- Update ARTIST_GUIDE.md field reference and test JSON

docs/ARTIST_GUIDE.md

@@ -762,6 +762,7 @@ The `movement_style` changes how the player physically moves — slower speed, d
 | `animations` | string/object | No | `"auto"` (default) or explicit name mapping |
 | `movement_style` | string | No | Movement restriction: `"waddle"`, `"shuffle"`, `"hop"`, or `"crawl"` |
 | `movement_modifier` | object | No | Override speed/jump for the movement style (requires `movement_style`) |
+| `creator` | string | No | Author/creator name, shown in the item tooltip |
 | `animation_bones` | object | Yes | Per-animation bone whitelist (see below) |
 
 ### animation_bones (required)