A cap on the catalog's NVMe size: above it only the tail and the stored ranges

After reset 24 the catalog grew ~3.7 GB an hour (77 GB, root 31 GB free, 600k
history ranges to go). CATALOG_MAX_NVME_GB (as voyager 1's
BACKFILL_MAX_NVME_GB): once the default tablespace is over it, leases and the
prefetcher take priority < 0 only (the tail, the stored ranges); measured once
a minute. Off when unset; 90 on homelab.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

start/env.ts

@@ -61,6 +61,7 @@ export default await Env.create(new URL('../', import.meta.url), {
   LEASE_TTL_SECONDS: Env.schema.number.optional(),
   SPOOL_DIR: Env.schema.string.optional(),
   CORPUS_DIR: Env.schema.string.optional(),
+  CATALOG_MAX_NVME_GB: Env.schema.number.optional(),
   SPOT_GROUP: Env.schema.string.optional(),
   SPOT_BACKFILL: Env.schema.number.optional(),
   SPOT_EVERY_SECONDS: Env.schema.number.optional(),