## Summary
Replace `time.Tick()` with `time.NewTicker()` in the auto-prune
goroutine so it stops cleanly during graceful shutdown.
## Problem
`time.Tick` creates a ticker that can never be garbage collected or
stopped. While the prune goroutine runs for the process lifetime, it
won't stop during graceful shutdown — the goroutine leaks past the
shutdown sequence.
## Fix
- Create a `time.NewTicker` and a done channel
- Use `select` to listen on both the ticker and done channel
- Stop the ticker and close the done channel in the shutdown path (after
`poller.Stop()`)
- Pattern matches the existing `StartEvictionTicker()` approach
## Testing
- `go build ./...` — compiles cleanly
- `go test ./...` — all tests pass
Fixes#377
Co-authored-by: you <you@example.com>