Streaming accepted a chunked body cut at a chunk boundary as complete,
so the limit now comes from the client that reads the body, picked per
requested size. Script requests keep their own default, maxBodySize
accepts sizes like 10MiB, and files sarin downloads for itself are
capped at 64MiB.
Refactor request generators to populate a script.RequestData intermediate struct, then apply it to fasthttp.Request in one step. This eliminates the round-trip conversion (fasthttp → RequestData → fasthttp) when scripts are enabled. Remove the URL field from RequestData and the now-unused fasthttp conversion functions from chain.go.
Replace ad-hoc fmt.Errorf/errors.New calls with typed error structs across config, sarin, and script packages to enable type-based error handling. Add script-specific error handlers in CLI entry point. Fix variable shadowing bug in Worker for scriptTransformer. Bump Go to 1.25.7 and golangci-lint to v2.8.0.
aykhans