📝 update CHANGELOG for depth sorting (PR #32)

CHANGELOG.md

@@ -7,6 +7,10 @@ Format follows [Keep a Changelog](https://keepachangelog.com/en/1.0.0/).
 
 ## [Unreleased]
 
+### Fixed
+- **Y-based depth sorting** (Issue #31): trees, rocks, seedlings and buildings now use `tileY + 5` as depth instead of fixed values — objects lower on screen always render in front of objects above them, regardless of spawn order; build ghost moved to depth 1000
+- **Nisse always visible** (Issue #33): Nisse sprites fixed at depth 900, always rendered above world objects
+
 ### Added
 - **Försterkreislauf** (Issue #25):
   - **Setzlinge beim Fällen**: Jeder gefällte Baum gibt 1–2 `tree_seed` in den Stockpile