Store, validated types, bounded pipeline, no-clobber extraction

The store reads and writes the Go on-disk format (it opens the oracle's
fixture vault). Object I/O runs on one bounded worker pool with eight
reusable cleared buffers; sequential and parallel runs produce identical
bytes under seeded test randomness. Extraction publishes with
RENAME_NOREPLACE/link and only after full authentication; failed or
after-publish writes keep crash-safe ordering.

Co-Authored-By: Claude <noreply@anthropic.com>

Cargo.lock

@@ -1236,6 +1236,7 @@ version = "1.9.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "e13084392c5e4bc371903e2935a5eaeed24905a7511356b883835e18a78f6879"
 dependencies = [
+ "serde",
  "zeroize_derive",
 ]