01c34db450
- Replaced snapshot internals with full-file records and removed contiguous/sparse snapshot APIs. - Added file-hash normalization, computed `computeFileHash`, and updated grammar/messages to 4-hex tags. - Simplified recovery by checking whole-file hashes first, then applying merge-replay fallback after mismatches. - Updated coding-agent tools to use `record`/`recordFileSnapshot` and skip hash headers for unsnapshotted large files. - Expanded patcher and snapshot tests to verify 4-hex anchors, hash deduplication, and cache-capped behavior.