Use uniform Overworld skylands generation

docs/PORTING.md

@@ -248,9 +248,10 @@ honor the server's loaded data packs. Automated coverage also verifies that a
 live Age's seed equals its immutable saved definition; Dynamic Dimensions
 derives both from the Overworld seed and the Age dimension identifier.
 
-Version 0.2.16.12 gives Cave and Island/Skylands Ages Overworld biomes, sky,
-weather, lighting, and day/night behavior while retaining their distinct
-terrain density: enclosed Nether-shaped caves and End-shaped floating islands.
+Version 0.2.16.13 gives Cave and Island/Skylands Ages Overworld biomes, sky,
+weather, lighting, and day/night behavior while retaining distinct terrain.
+Caves remain enclosed. Skylands use Minecraft's uniform floating-island noise
+and Overworld-like surfaces without the End's central dragon island.
 
 Version 0.2.14.0 restores the legacy Linking and Descriptive Book artwork for
 inventory items and gives each book its matching open-book texture when placed

gradle.properties

@@ -35,7 +35,7 @@ mod_name=Rivencraft
 # The license of the mod. Review your options at https://choosealicense.com/. All Rights Reserved is the default.
 mod_license=LGPL-3.0-or-later
 # The mod version. Rivencraft uses the x.y.z.b policy documented in README.md.
-mod_version=0.2.16.12
+mod_version=0.2.16.13
 immersive_portals_version=6.0.7
 # The group ID for the mod. It is only important when publishing as an artifact to a Maven repository.
 # This should match the base package used for the mod sources.

src/main/java/net/dnorberg/rivencraft/book/AgeDimensionService.java

@@ -214,15 +214,15 @@ public final class AgeDimensionService {
         if (profile.equals(AgeGenerationProfiles.CAVE)) {
             settingsKey = NoiseGeneratorSettings.NETHER;
         } else if (profile.equals(AgeGenerationProfiles.ISLAND)) {
-            settingsKey = NoiseGeneratorSettings.END;
+            settingsKey = NoiseGeneratorSettings.FLOATING_ISLANDS;
         } else if (profile.equals(AgeGenerationProfiles.AMPLIFIED)) {
             settingsKey = NoiseGeneratorSettings.AMPLIFIED;
         } else {
             settingsKey = NoiseGeneratorSettings.OVERWORLD;
         }
-        // Cave retains enclosed Nether-shaped density and Island/Skylands
-        // retains floating End-shaped density. All profiles use Overworld
-        // biomes and the Overworld dimension type for sky and time behavior.
+        // Cave retains enclosed Nether-shaped density. Island/Skylands uses
+        // uniform floating-island density without the End's central dragon
+        // island. Both use Overworld biomes and dimension environment.
         // random_vanilla is retained as a migration alias for existing Ages.
         return new NoiseBasedChunkGenerator(
                 MultiNoiseBiomeSource.createFromPreset(