Show and update the Codex CLI used by GSwitch

[squarepots]

User impact

GSwitch depends on the locally installed Codex CLI for account checks, but users cannot see which CLI version it uses or update it from GSwitch. A CLI startup failure currently sends users to an external manual step.

Requested behavior

• Show the version of the same Codex CLI executable that GSwitch uses.
• Offer an explicit update action through the CLI's official codex update command when that command is supported.
• Block the update while an external Codex runtime or another GSwitch account operation is active.
• Recheck and display the CLI version after the command; keep installation and update failures actionable without exposing raw command output.
• Keep saved accounts and Codex credentials untouched. Do not update automatically.

Acceptance

• English and Simplified Chinese show installed, missing, updating, success, and failure states.
• A CLI without an update subcommand offers official manual guidance rather than treating update as a prompt.
• Tests use a fake CLI or mocks; they do not update the maintainer's installed CLI or operate on real accounts.
• Deliver the feature with the next public Windows release and keep the account-switching issue open until real-account verification.

[squarepots]

Delivered in public v1.0.9: https://github.com/ginbing/GSwitch/releases/tag/v1.0.9 . The Windows installer is https://github.com/ginbing/GSwitch/releases/download/v1.0.9/GSwitch_1.0.9_x64-setup.exe . PR #127 adds the installed CLI version, explicit supported update action, localized status and errors, official manual guidance, and the Codex/GSwitch operation guard. Focused fake-CLI tests and the exact-tag release workflow passed: https://github.com/ginbing/GSwitch/actions/runs/36057637236 . No real CLI update or account operation was run during testing. Closing this delivered feature; report any installed-build regression as a follow-up.