fix(extraction): count all file-level-tracked langs (incl .properties) as indexed (#544)

Completes #357. The no-symbol file-level class is yaml/twig/properties, but the
count fix only covered yaml/twig — so a .properties-only project still printed
"No files found to index" even though the files were stored. Introduce a single
isFileLevelOnlyLanguage predicate (the canonical set behind the tree-sitter
no-symbol branch, xml excluded since its MyBatis extractor emits a file node)
and use it at both count sites and the extraction dispatch so the list can't
drift. Adds .properties regression coverage for indexAll() and indexFiles().

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

src/extraction/grammars.ts

@@ -290,6 +290,19 @@ export function isGrammarLoaded(language: Language): boolean {
   return languageCache.has(language);
 }
 
+/**
+ * Languages tracked at the file-record level only: parsing emits zero symbol
+ * nodes, but the file is still stored (and framework resolvers may add per-file
+ * references later, e.g. Drupal routing yml, Spring `@Value` against
+ * application.properties). This is the canonical set behind the no-symbol
+ * branch in `tree-sitter.ts`; `xml` is intentionally excluded because its
+ * MyBatis extractor emits a file node. Callers use this to count such files as
+ * indexed rather than skipped, so it must stay in sync with that branch.
+ */
+export function isFileLevelOnlyLanguage(language: Language): boolean {
+  return language === 'yaml' || language === 'twig' || language === 'properties';
+}
+
 /**
  * Get all supported languages (those with grammar definitions).
  */