Use ComSpec-aware shell selection for escaped wrapper launches.
Apply it to the remaining Windows Claude launch paths.
Rewrite the Codex exec regression test to use scoped spies so the full suite stays isolated.
Align Windows .cmd/.bat launch behavior with the Codex detector shell contract.
This keeps escaped -c overrides intact through wrapper execution.
Adds regression coverage for the Codex runtime path and the shared Windows shell launch path.