Migrate index state tracking from filesystem sentinel files to an on-disk JSON schema within `index.meta`. The `IndexMeta` struct is now wrapped in an `Arc` with internal locking, exposing only fallible methods for genome and state access. In-memory mutation capabilities have been removed, requiring callers to handle I/O errors explicitly and pass immutable references to downstream components like `PartitionRouter`. Public sentinel constants have been removed from exports.
Eric Coissac
8d6ba6546b