feat: Pods fields in Theme Builder bodies checked against the template's post types (E12)

Both forms Divi writes are recognized (ruling Q11): custom_meta_<key> and the
dialog form post_meta_key + select_meta_key. Choice fields get a note about the
stored value, relation fields name IDs (F4). Only templates the user may edit
are checked or named; others are counted (Q21 pattern). Warnings only, also in
the dry run of a live body. DynamicFields extracted from lit/divi-dynamic-sources.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>

tests/Unit/Integrations/Divi/Compose/VariableRefTest.php

@@ -519,4 +519,12 @@ final class VariableRefTest extends TestCase
         $this->expectExceptionMessage('nur in Link- und URL-Feldern');
         $ref->canonical($link, ComposeFixture::sanitizer());
     }
+
+    public function testNameOfReadsTheContentOptionOnly(): void
+    {
+        self::assertSame('custom_meta_role', VariableRef::nameOf(self::content('custom_meta_role', '{}')));
+        self::assertNull(VariableRef::nameOf('$variable({"type":"color","value":{"name":"gcid-primary","settings":{}}})$'));
+        self::assertNull(VariableRef::nameOf('Text'));
+        self::assertNull(VariableRef::nameOf('$variable(kaputt)$'));
+    }
 }