The test that each changing command waits for the state directory lock
slept a fixed 100 ms per command. It now polls the goroutine stacks until
the command is parked in vault.LockStateDir, checks the state directory
is unchanged, and releases the lock; a command that takes no lock still
fails by finishing first.
newTwoVaultFs creates its two vaults, each with a passphrase unlocker,
once, and returns a fresh copy of them on every call, so the six path and
move tests no longer each pay for two passphrase key derivations.
Model: opus-5-5
sneak