Build directory conformance, fault-injection, and crash-recovery suites

[kylebernhardy]

Outcome

Prove that both storage modes satisfy the wrapper contract and that Rocks mode satisfies Tantivy Directory under failure.

Acceptance criteria

• A shared conformance suite runs against native and Rocks modes.
• Tests cover repeatable flush, immutable slices, locks, watch, atomic metadata, delete races, missing files, writer death, and recovery.
• Crash points cover object writes, visibility flush, termination, durability barrier, metadata publication, reload, GC, and generation swap.
• Property/state-machine tests exercise lifecycle and concurrent operations.
• Sanitizers and native panic/error injection run in CI where supported.
• Failures produce durable, actionable status rather than silent watermark advancement or process corruption.

Comment generated by kAIle (Codex GPT-5)