Add per-crate variant_ctx() helper methods to StorageError, BlobCacheError, ProtocolError, and BridgeError. Replace 78 .map_err(|e| format!(...)) closures with concise context calls. Identical error messages preserved.
Add per-crate variant_ctx() helper methods to StorageError, BlobCacheError, ProtocolError, and BridgeError. Replace 78 .map_err(|e| format!(...)) closures with concise context calls. Identical error messages preserved.