new cl package; delete deprecated files

[xushiwei]

No description provided.

[fennoai]

Review: scaffold cl package, remove legacy _xtool/internal

This is a clean scaffolding PR. It removes the entire _xtool/internal/* tree and introduces a skeleton cl/compile.go (types + a NewPackage stub that panic("todo")), and adds github.com/goplus/gogen v1.23.5.

Verified:

• No dangling references to the deleted _xtool/internal packages remain anywhere in the repo.
• cl/compile.go imports all resolve; go vet ./cl/ is clean. (Full go build ./... fails only on llgo/C relocation targets, which require the llgo toolchain and are unrelated to this diff.)
• go.mod/go.sum are consistent; gogen v1.23.5 is a legitimate release from the same goplus org, with well-formed module + go.mod hashes.

Findings: only two minor, non-blocking doc-comment nits (inline). No correctness, security, or performance issues — performance review is naturally deferred until NewPackage is implemented.

[fennoai]

[P3] Exported type PkgInfo has no doc comment

PkgInfo is exported but undocumented, while every other exported type in this file (Package, Reused, Config, Source) carries a doc comment. This will trip revive/golint's "exported type should have comment" check. Consider adding a // PkgInfo ... comment before merge.

[fennoai]

[P3] Config.Reused field comment duplicates the Reused type comment

The comment on the embedded *Reused field is verbatim identical to the Reused type's own doc comment (line 38), so it adds no information beyond the type doc. Consider trimming it (e.g. // Reused, if set, reuses a Package instance across headers.).