fix: metadata-only update() never rewrites the noun record — the unconditional whole-vector save turned per-entity stat touches into full rewrites+fsync, amplifying read-heavy sweeps into disk saturation on a production deployment

Also: idle PathResolver stats tick no longer logs NaN% every minute (logs
only on new traffic, via prodLog); graph-lsm-* key family recognized as
system resources (kills the per-boot unknown-key warning on provider-backed
brains). Four regression pins in tests/integration/update-write-granularity.

src/storage/baseStorage.ts

@@ -382,6 +382,10 @@ export abstract class BaseStorage extends BaseStorageAdapter {
                                          // identical to the unknown-key fallback these keys hit
                                          // before being listed here — this only kills the
                                          // per-boot "Unknown key format" warning)
+      id.startsWith('graph-lsm-') ||     // Graph-LSM store manifests written through storage by
+                                         // an active native graph provider — same
+                                         // warn-then-route fallback as above; listing the family
+                                         // silences the per-boot warning on provider-backed brains
       isSingletonSystemKey(id)           // Known singletons (e.g. brainy:entityIdMapper) hit the
                                          // same warn-then-route fallback without this — the
                                          // routing below already handles them identically