Add Fabric entrypoint to allow other mods to register providers safely.

common/src/main/java/li/cil/tis3d/api/platform/FabricProviderInitializer.java

@@ -0,0 +1,14 @@
+package li.cil.tis3d.api.platform;
+
+/**
+ * Fabric specific interface, used to define an entrypoint that is invoked when all
+ * TIS-3D owned registries have been created, and entries may be registered with
+ * them. This is Fabric's approach to allowing ordered initialization. For Forge this
+ * is not required, since it allows declaring mod initialization ordering.
+ */
+public interface FabricProviderInitializer {
+    /**
+     * Registers providers with provider registries.
+     */
+    void registerProviders();
+}

common/src/main/java/li/cil/tis3d/api/platform/package-info.java

@@ -0,0 +1,7 @@
+@ParametersAreNonnullByDefault
+@MethodsReturnNonnullByDefault
+package li.cil.tis3d.api.platform;
+
+import net.minecraft.MethodsReturnNonnullByDefault;
+
+import javax.annotation.ParametersAreNonnullByDefault;

fabric/src/main/java/li/cil/tis3d/client/fabric/ClientBootstrapFabric.java

@@ -1,5 +1,6 @@
 package li.cil.tis3d.client.fabric;
 
+import li.cil.tis3d.api.platform.FabricProviderInitializer;
 import li.cil.tis3d.client.ClientBootstrap;
 import li.cil.tis3d.client.ClientSetup;
 import li.cil.tis3d.client.renderer.Textures;
@@ -11,6 +12,7 @@
 import net.fabricmc.fabric.api.client.model.ModelLoadingRegistry;
 import net.fabricmc.fabric.api.event.client.ClientSpriteRegistryCallback;
 import net.fabricmc.fabric.api.event.client.player.ClientPickBlockGatherCallback;
+import net.fabricmc.loader.impl.entrypoint.EntrypointUtils;
 import net.minecraft.world.inventory.InventoryMenu;
 import net.minecraft.world.item.ItemStack;
 import net.minecraft.world.level.block.entity.BlockEntity;
@@ -22,6 +24,8 @@ public void onInitializeClient() {
         ClientBootstrap.run();
         ClientSetup.run();
 
+        EntrypointUtils.invoke("tis3d:registration", FabricProviderInitializer.class, FabricProviderInitializer::registerProviders);
+
         ClientChunkEvents.CHUNK_UNLOAD.register((level, chunk) -> {
             for (final BlockEntity blockEntity : chunk.getBlockEntities().values()) {
                 if (blockEntity instanceof final ChunkUnloadListener listener) {