fix(ci): isolate packed Python syntax checks from ambient imports
Keep caller-local modules and site startup hooks from replacing the
standard-library AST/tar readers or executing during package validation.
Assisted-by: Reimu (gensokyo-skills:reimu-incident-triage)
Assisted-by: Kogasa (gensokyo-skills:kogasa-surprise-testing)
Parse only the exact regular packed Python bridge member without extracting into the caller-owned private runtime root. Preserve required Ghidra admission, typed callers, native lease ownership and cleanup on success or failure.
Validation: 263 focused real tar/Python/ownership and CI selection checks, 42 official WABT packaged CLI/MCP cases, full check:ci/check:fast/actionlint, real-package alternating measurements and exact-head hosted CI passed. The required Windows lane exercises the retained native lease without skipping missing authority.
Fixes#4134.
Co-authored-by: abdooo2235 <abdalrhmantheiv15@gmail.com>
gensokyo-dev