indigo: replace collectiondir with lightrail
lightrail (fig's Rust collection directory) replaces the Go collectiondir
sidecar, which had unbounded memory growth (~1.4 GiB and climbing toward
its OOM limit). lightrail validates sync 1.1 commit proofs, removes repos
on collection deletion, and has a configurable fjall cache.
- add Dockerfile.lightrail, helm values, and ServiceMonitor
- route listReposByCollection to lightrail in ingress
- replace collectiondir grafana panels with lightrail metrics
- remove collectiondir backfill recipe from justfile
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>