sibling explicit-grouping implementation: commit all work, removal of stray scratch files; update docs and status; keep P1 fix and other senior details

config/container.php

@@ -58,6 +58,14 @@ return static fn (AppConfig $config): array => [
     CatalogServiceInterface::class => DI\get(CatalogService::class),
     LegacyGuessedImportGroupingAdapter::class => static fn (ContainerInterface $c): LegacyGuessedImportGroupingAdapter
         => new LegacyGuessedImportGroupingAdapter($c->get(CatalogRepositoryInterface::class)),
+    // Explicit grouping is opt-in; the default ImportService below remains legacy-compatible.
+    \MeshVault\Indexer\ExplicitImportGroupingAdapter::class => static fn (ContainerInterface $c)
+        => new \MeshVault\Indexer\ExplicitImportGroupingAdapter(
+            $c->get(CatalogRepositoryInterface::class),
+            $c->get(ImportJobRepositoryInterface::class),
+        ),
+    \MeshVault\Indexer\Contracts\ExplicitImportGroupingAdapterInterface::class
+        => DI\get(\MeshVault\Indexer\ExplicitImportGroupingAdapter::class),
     ImportService::class => static fn (ContainerInterface $c): ImportService => new ImportService(
         $c->get(FileEnumeratorInterface::class),
         $c->get(ImportJobRepositoryInterface::class),