Merge pull request #4 from morluto/main

docs: rewrite SKILL.md as Magpie language programming guide for LLM agents

Guard decode free with per-local consumed state

Track decode consumption across non-phi CFG joins

Prevent duplicate decode ownership on arc.retain

Fix path-sensitive decode ownership tracking across CFG

fix(codegen): free conflicting decode-type phi payloads safely

fix(parse-json): tighten TResult error type and phi ownership safety

fix(codegen): preserve decode ownership across mixed phi inputs

fix(codegen): transfer decode ownership metadata on Move

fix(codegen): clear decode ownership after value ArcRelease

chore(fmt): apply rustfmt to llvm codegen

feat(parse-json): finalize try-ffi migration and cleanup warnings

fix(parse-json): enforce decode rawptr<u8> shape and null-input errors

docs: update all documentation for GPU multi-backend expansion and monomorphization