docs(java-metadata): fix stale 'static self-registration' comments

Pre-merge review follow-up: three comments still described the removed
self-registering static{} blocks. Reword to point at the ServiceLoader
provider path so they no longer contradict the anti-cycle notes.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Author: dmealing

server/java/metadata/src/main/java/com/metaobjects/MetaData.java

@@ -128,7 +128,7 @@ public class MetaData implements Cloneable, Serializable {
     /** Root metadata subtype for the tree-root node (MetaRoot) */
     public static final String SUBTYPE_ROOT = "root";
 
-    // Unified registry self-registration for root metadata type
+    // Registered via CoreTypeMetaDataProvider on the ServiceLoader bootstrap.
     /**
      * Register MetaData as metadata.base with abstract requirements constraints.
      * This creates metadata.base which defines metadata file structure and enforces
@@ -372,7 +372,7 @@ public MetaData(String type, String subType, String name ) {
 
     // ========== ENHANCED TYPE SYSTEM METHODS ==========
 
-    // Type definition methods removed - using unified registry with static self-registration
+    // Type definition methods removed - using unified registry via ServiceLoader providers
 
     /**
      * Validate MetaData name during construction

server/java/metadata/src/main/java/com/metaobjects/MetaRoot.java

@@ -69,16 +69,14 @@ public class MetaRoot extends MetaData {
 
     /**
      * Registers the metadata.root type with the supplied registry.
-     * Provided for parity with {@link MetaData#registerTypes(MetaDataRegistry)};
-     * the static initializer already self-registers against the singleton.
+     * Invoked via CoreTypeMetaDataProvider on the ServiceLoader bootstrap.
      *
      * @param registry the registry to register with
      */
     public static void registerTypes(MetaDataRegistry registry) {
         try {
-            // Idempotent: the static block (singleton) and the ServiceLoader
-            // bootstrap (CoreTypeMetaDataProvider, for isolated registries) both
-            // call this; skip if metadata.root is already registered.
+            // Idempotent: skip if metadata.root is already registered (the
+            // provider may run against a registry that already has it).
             if (registry.isRegistered(TYPE_METADATA, SUBTYPE_ROOT)) {
                 return;
             }