Server-side session storage port.
Implemented by the plugin's MemorySessionStore and CacheSessionStore, and
by any application-supplied backend. Only the store strategy uses it; the
default cookie strategy keeps the payload in the cookie and needs no store.
Every method is async so a network-backed store fits without change.
read(id: string): Promise<SessionData | null>
Reads a stored session payload.
write(): Promise<void>
Writes a session payload, replacing any existing one.
destroy(id: string): Promise<boolean>
Removes a stored session.
isHealthy(): Promise<boolean>
Reports the store's reachability, for the plugin's health indicator.
Optional: a store with no meaningful liveness check omits it, and the indicator then reports only that a store is configured.
close(): Promise<void>
Releases resources held by the store (timers, connections).
Optional: called from the plugin's onClose. A store holding nothing
omits it.