Optional durability for the annotation Annotai.Store.

Opt-in via app config. When enabled, this GenServer:

• hydrates the Store from the on-disk snapshot on boot (pruning terminal annotations older than the optional TTL),
• debounces a snapshot write after each mutation, so a burst of edits collapses into one disk write off the mutation hot path, and
• flushes a final time on graceful shutdown.

The Store pokes this process (GenServer.cast(_, :changed)) after every mutation; the poke is a no-op when persistence is disabled, so the Store stays fully decoupled. The actual encode/write lives behind Annotai.Persistence.Adapter (default Annotai.Persistence.Adapter.File).

Config

config :annotai, persistence: false                              # (default) off
config :annotai, persistence: true                               # on, defaults
config :annotai, persistence: [path: "...", ttl: {14, :day}]     # on, overrides

Config deep-merges keyword lists across env files, so override per env by setting the whole value (e.g. persistence: false in test.exs), not partial keys.