- Add BATCH_RETRY_LIMIT and BATCH_RETRY_DELAY constants after DEFAULT_BATCH_SIZE
- Add _insert_batch_with_retry() helper with exponential backoff
- Replace both bare try/except insert blocks in _build_collection_from_bulk
with calls to the retry helper so transient ChromaDB errors are retried
up to BATCH_RETRY_LIMIT times before a batch is counted as failed