Unboxed biome selection

- Rarity selection streams pick from precomputed cumulative tables
- Implode and surface biome fixes take primitive coordinates
- Child selection reuses one derived child seed instead of a new RNG per level
- Base biome selection reads bridge and inferred streams directly

core/src/test/java/art/arcane/iris/generation/runtime/IrisComplexSelfSelectionTest.java

@@ -83,7 +83,7 @@ public class IrisComplexSelfSelectionTest {
             Field field = IrisComplex.class.getDeclaredField("childSelectionPlans");
             field.setAccessible(true);
             field.set(complex, plans);
-            implode = IrisComplex.class.getDeclaredMethod("implode", IrisBiome.class, Double.class, Double.class, int.class);
+            implode = IrisComplex.class.getDeclaredMethod("implode", IrisBiome.class, double.class, double.class, int.class);
             implode.setAccessible(true);
         }
 
@@ -106,7 +106,7 @@ public class IrisComplexSelfSelectionTest {
         }
 
         @Override
-        public CNG getChildrenGenerator(RNG rng, int signature, double scale) {
+        public CNG getChildrenGenerator(long seed, double scale) {
             return noise;
         }
     }

core/src/test/java/art/arcane/iris/generation/stage/IrisCarveModifierInferenceIsolationTest.java

@@ -97,11 +97,11 @@ public class IrisCarveModifierInferenceIsolationTest {
         doReturn(0D).when(region).getShoreHeight(anyDouble(), anyDouble());
         Method fixBiomeType = IrisComplex.class.getDeclaredMethod(
                 "fixBiomeType",
-                Double.class,
+                double.class,
                 IrisBiome.class,
                 IrisRegion.class,
-                Double.class,
-                Double.class,
+                double.class,
+                double.class,
                 double.class
         );
         fixBiomeType.setAccessible(true);