[MeSouls]

Summary

Windows switch-and-start was replacing a user-selected portable ChatGPT.exe with the registered Microsoft Store Codex package.

• Keep an existing unpackaged ChatGPT.exe even when a Store package is registered.
• Do not treat a failed PE read of that selected file as permission to overwrite it.
• Still migrate an official legacy Store Codex.exe to ChatGPT.exe, and still refresh a stale Store install of the same package family.
• Still reject CLI resources\codex.exe, DLLs, and scripts as the desktop entry.
• Default launch uses the configured unpackaged exe instead of the Store AppUserModelId.

Test plan

• cargo test explicit_unpackaged_chatgpt_exe_is_not_replaced_by_store_default --lib in src-tauri (Windows)
• Set Codex launch path to a portable ChatGPT.exe outside WindowsApps, then switch account and start. The saved path must stay on that exe.
• A missing unpackaged path, or a CLI codex.exe, may still be replaced by the detected Store app.
• A stale Store path under the same package family may still be refreshed.