perf: double populate budget in release builds

512 chunks/frame in debug, 1024 in release. In release, recolor runs
~2x faster so 1024 still costs ~1ms but clears the dirty queue twice
as fast, closing the p99 gap during rapid z-scrolling.

src/world/tiles/tilemap_chunk.rs

@@ -57,7 +57,10 @@ impl Default for TilemapChunkSpawner {
     }
 }
 
+#[cfg(debug_assertions)]
 pub const MAX_POPULATE_PER_FRAME: usize = 512;
+#[cfg(not(debug_assertions))]
+pub const MAX_POPULATE_PER_FRAME: usize = 1024;
 
 #[derive(Resource)]
 pub struct PreviousZIndex(pub i32);