Documentation only. Corrects the ARCHITECTURE.md chunk sizes and the fx
config type; documents the process-wide PID lock, the `ls`/`rm` aliases,
`VAULTIK_CPUPROFILE`/`VAULTIK_MEMPROFILE`, the `age_secret_key` key and
its threat-model caveat, and how zstd levels 1-19 collapse onto four
presets; narrows the output-style claim to match reality; and links
ARCHITECTURE.md and config.example.yml from the README. The two
behaviour changes the sweep surfaced are deferred to #149 (route direct
stdout through internal/ui) and #150 (scope the lock), each linked from
the text. DATAMODEL.md and REPOSTRUCTURE.md were already linked.
model: claude-opus-4-8
sneak