Phase 3 foundations (task 1): src/lib/xrpc-error.ts matches both the old
@atproto/api XRPCError and lex-client XrpcError/XrpcResponseError during
the migration; errors.ts token-invalid matching goes through it. toLex<T>()
added to #/types/bsky as a marked interim cast for mixed-world boundaries.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Samuel Newman