fix: resolve import hang and index rebuild data loss bugs

Critical Bug Fixes (v3.43.2):

Bug #1 - Import Infinite Loop:
- Fix placeholder entity infinite loop in ImportCoordinator
- Use exact matching instead of fuzzy .includes() for entity names
- Search entities array (not rows) for existing placeholders
- Add duplicate relationship prevention in brain.relate()

Bug #2 - Index Rebuild File Discovery:
- Fix fileSystemStorage to scan sharded subdirectories
- Update getAllNodes() to use getAllShardedFiles()
- Update getAllEdges() to use getAllShardedFiles()
- Update getNodesByNounType() to use getAllShardedFiles()
- Fix getStorageStatus() to use O(1) persisted counts

Additional Improvements:
- Add brain.flush() API for explicit index persistence
- Make GraphAdjacencyIndex.flush() public
- Add auto-flush at end of import pipeline
- Update duplicate relationship test to expect deduplication

Files Modified:
- src/storage/adapters/fileSystemStorage.ts
- src/import/ImportCoordinator.ts
- src/brainy.ts
- src/graph/graphAdjacencyIndex.ts
- tests/unit/brainy/relate.test.ts

package-lock.json

@@ -1,12 +1,12 @@
 {
   "name": "@soulcraft/brainy",
-  "version": "3.43.0",
+  "version": "3.43.1",
   "lockfileVersion": 3,
   "requires": true,
   "packages": {
     "": {
       "name": "@soulcraft/brainy",
-      "version": "3.43.0",
+      "version": "3.43.1",
       "license": "MIT",
       "dependencies": {
         "@aws-sdk/client-s3": "^3.540.0",