Build the Linux LLVM helper and runtime pack before running both test lanes, and align native cache contracts with the current target policy. Full managed Sandbox gate passed.
* feat(compiler): add native LLVM object emission - ship the pinned macOS arm64 LLVM helper and platform package - add assembly/object CLI outputs, caching, diagnostics, and runtime ABI checks - validate helper artifacts through CI, packaging, docs, and differential coverage * fix(compiler): harden native LLVM emission * fix(compiler): harden LLVM helper packaging * fix(compiler): stabilize LLVM helper package size * fix(compiler): harden native helper validation * fix(compiler): harden LLVM helper verification * fix(compiler): harden native object emission