Merge commit 'd803bfe2b1fe7f5e219e50ac20d6801a0a58ac75' as 'vendor/ruvector'

vendor/ruvector/crates/rvf/rvf-manifest/README.md

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+# rvf-manifest
+
+Two-level manifest system for tracking RVF segments and coordinating compaction.
+
+## Overview
+
+`rvf-manifest` manages the metadata layer that tracks which segments are active, tombstoned, or pending compaction:
+
+- **Level-0 manifest** -- per-file segment directory with CRC32c integrity
+- **Level-1 manifest** -- cross-file global index for multi-file stores
+- **Compaction coordination** -- tracks merge candidates and generation numbers
+
+## Usage
+
+```toml
+[dependencies]
+rvf-manifest = "0.1"
+```
+
+## Features
+
+- `std` (default) -- enable `std` I/O support
+
+## FileIdentity Storage
+
+The `FileIdentity` struct (68 bytes) is stored at offset `0xF00` within the Level0Root reserved area (252 bytes starting at the end of the signature region). This placement is backward compatible: old readers that ignore the reserved area see zeros and continue working normally.
+
+| Offset | Size | Field |
+|--------|------|-------|
+| `0xF00` | 16 | `file_id` |
+| `0xF10` | 16 | `parent_id` |
+| `0xF20` | 32 | `parent_hash` |
+| `0xF40` | 4 | `lineage_depth` |
+
+The `read_level0()` and `write_level0()` functions in this crate transparently read and write the `FileIdentity` at these offsets. The CRC32C checksum at offset `0xFFC` covers the entire 4092-byte region including the FileIdentity bytes, ensuring integrity.
+
+## License
+
+MIT OR Apache-2.0