Datapack export

- /iris datapack export compiles one pack dimension into a worldgen datapack for Minecraft 26.3 and later
- Bukkit and mod loaders take the same version, mode, namespace, output, format, objects and replace arguments
- The default overworld mode replaces the Overworld of a new world with the default world type
- Preset and dimension modes write a selectable world preset or a separate dimension
- The export runs in the background and publishes the zip or folder atomically
- Pack compiler stages turn noise, terrain, caves, subterrain, biomes, surface, decoration, objects and structures into a version-neutral IR
- Capability lowering fits every field to 26.3 density function ranges
- Disjoint min and max nodes fold to the input that always wins
- The 26.3 writer emits density functions, noise settings, biomes, features, structures, presets and dimensions
- Every export carries the Iris logo as its pack.png
- Unused objects, templates and features are pruned from the output
- The pruner keeps pack.png without reading references from its bytes
- Imported pack datapacks are bundled into the export
- Every approximation reports an export limit diagnostic
- Generation cost is counted against a node budget and reported as a warning
- Cave biomes over the wall palette limit use the closest kept palette
- Jigsaw exports share the template encoder, block states, destinations and publisher with the worldgen export
- DataVersion carries the pack format minor and world data version
- Both platforms expose vanilla data from the server classpath
- GoldenHashEngine and the export probes share one chunk spiral scan
- Headless 26.3 probes measure export cost and compare column and chunk likeness against Iris
- Real-codec tests decode the exported resources with the 26.3 registries
- Paper registry tests run in isolated registry scopes
- Command help and messages cover the export in every language file

spi/src/main/java/art/arcane/iris/spi/IrisPlatform.java

@@ -68,6 +68,8 @@ public interface IrisPlatform {
      */
     PlatformBiomeWriter biomeWriter();
 
+    VanillaDataSource vanillaData();
+
     default Class<?> classifyMantleValue(Object value) {
         return value.getClass();
     }

spi/src/main/java/art/arcane/iris/spi/VanillaDataSource.java

@@ -0,0 +1,10 @@
+package art.arcane.iris.spi;
+
+import java.util.List;
+import java.util.Optional;
+
+public interface VanillaDataSource {
+    Optional<byte[]> read(String dataPath);
+
+    List<String> list(String prefix);
+}

spi/src/test/java/art/arcane/iris/spi/IrisPlatformsBindContractTest.java

@@ -121,6 +121,11 @@ public class IrisPlatformsBindContractTest {
             throw new UnsupportedOperationException();
         }
 
+        @Override
+        public VanillaDataSource vanillaData() {
+            throw new UnsupportedOperationException();
+        }
+
         @Override
         public File dataFolder() {
             throw new UnsupportedOperationException();