Acknowledge review completion for Hashbox v0.8

[Copilot]

User requested review restart after 111 commits. All previous automated review feedback has been addressed and resolved.

Verified Resolutions:

• Sync watermark keys now scope to account+dataset (60b53ed) - prevents cross-account collision
• skipDataGap returns errors instead of panicking (266986a) - enables graceful recovery
• Shell variable expansion uses proper quoting (Fix unsafe POSIX shell variable expansion in docker_sync.sh #3, 3cdde88) - POSIX-safe
• File descriptor leaks fixed in GC/verify/integrity paths (62ee8ae, f1c7858) - proper cleanup on all code paths
• Docker e2e ports bound to 127.0.0.1 (89a4186) - prevents unintended network exposure
• Connection close errors logged without panic (1c5788c) - allows deferred recovery to complete
• Dataset hash lookups use precomputed values (61baad0) - eliminates redundant hashing

Working tree clean. Ready for human review.

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