- collectShardFiles was only scanning merged/ root and merged/YYYY/MM/DD/
  but mergeFiles writes to merged/YYYY/merged-*.json (year level only)
- Added year-level scan in collectShardFiles to find merged files
- Fixed isMergedFile to exclude merged-up-to-* lock files (require .json)
- Updated zen-fs-webdav dependency to ^0.1.7
- Bump version to 1.0.13