feat: data-oriented chunks optimization with tile registry

- Phase 1: Bit-packed standability (ChunkData with bitsets)
- Phase 2: Reactive connectivity (dirty chunks)
- Phase 3: Async terrain baking (AsyncComputeTaskPool)
- Pathfinding weight system (rock=50 preferred, bedrock=150 avoided)
- Movement speed affected by tile weight
- External tiles.toml for hot-reloadable tile definitions
- TileRegistry singleton for async-safe tile lookups
- Fixed world_to_chunk to use CHUNK_SIZE_TILE (128) not CHUNK_SIZE (8)
- Fixed infinite spawner with Local<bool> state guards
- Fixed spawn coordinate grid alignment

Note: Zigzag pathfinding bug introduced - needs investigation

src/main.rs

@@ -5,6 +5,7 @@ use crate::entities::{
     item::{initialize_item_rotation_state, item_tile_management_system, ItemRotationTimer},
     livestock::pig::pig_drop_system,
 };
+use crate::game::SpawnDelay;
 
 mod camera;
 mod config;
@@ -25,6 +26,7 @@ fn main() {
         })
         .insert_resource(camera::CameraMoved(false))
         .insert_resource(world::tiles::QuiltCache::default())
+        .init_resource::<SpawnDelay>()
         .add_systems(PreStartup, world::textures::initialize_textures)
         .add_plugins(
             DefaultPlugins
@@ -45,13 +47,7 @@ fn main() {
         .add_plugins(entities::pathfinding::PathfindingPlugin)
         .add_systems(
             Startup,
-            (
-                camera::spawn_panning_camera,
-                cursor::setup_cursor,
-                entities::sentient::dorf::spawn_dorfs,
-                entities::livestock::pig::spawn_pigs,
-                entities::livestock::rabbit::spawn_rabbits,
-            ),
+            (camera::spawn_panning_camera, cursor::setup_cursor),
         )
         .add_systems(
             Update,
@@ -60,6 +56,9 @@ fn main() {
                 camera::camera_z_movement,
                 camera::camera_movement,
                 cursor::move_cursor,
+                entities::sentient::dorf::spawn_dorfs,
+                entities::livestock::pig::spawn_pigs,
+                entities::livestock::rabbit::spawn_rabbits,
             ),
         )
         .add_systems(Update, pig_drop_system)