Replace bulk json.load of the full manifest (which materializes the
entire JSON array into memory) with incremental ijson streaming.
Eliminates self.manifest entirely — records are never all in memory
at once.
- Add ijson>=3.2 dependency
- New module-level iter_manifest_records() generator
- load_manifest_files() collects paths only; no parsing at load time
- check_manifest_validity() streams without accumulating records
- decrypt_secret_fields() streams each manifest to a .decrypted.json
temp file record-by-record; temp files cleaned up after file copy
- _import_files_from_manifest() collects only document records (small
fraction of manifest) for the tqdm progress bar
Measured on 200 docs + 200 CustomFieldInstances:
- Streaming validation: peak memory 3081 KiB -> 333 KiB (89% reduction)
- Stream-decrypt to file: peak memory 3081 KiB -> 549 KiB (82% reduction)
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
