Update 2.154

v2.154.0.0BETAMINORLulu

Sphere Grid Save Migration: sidecar C# read/write library + RT0 CLI

• New FfxSaveSphereGridExtraStateSidecar + FfxSaveSphereGridExtraStateSidecarIO library (atomic load/save, validate, Matches, BuildEmptyFromAnalyzer, merge helpers); CLI --spheregrid-sidecar-validate/create/info; sample work/_samples/sgm/sidecar_v1_minimal.json; path convention mods/Spira Reforge/save-sidecars/<profile>/<prefix>.sphere-grid-extra.json. Offline gates SGM-RT0-05/06

v2.153.0.0