Make explicit latest-update requests one-step and agent-driven

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Problem

The installed $update-wizard currently explains the package boundary and tells the user to run npx codex-sdlc-wizard@latest update. That is technically accurate but unnecessarily manual in Codex CLI/Desktop: when the user explicitly asks to update to latest, the agent can perform the package handoff itself.

Desired behavior

For an explicit latest-update request, the update skill should:

1. Check npm view codex-sdlc-wizard version when network is available.
2. Compare it with the active bundled/installed version.
3. Run npx codex-sdlc-wizard@latest update itself in the target repo when newer or when the user explicitly requested latest.
4. Run the package check/verification path.
5. Explain that the current process cannot hot-reload the replaced skill/hooks and instruct Codex to restart or reopen the repo once.

Do not silently self-update during ordinary drift repair, offline work, or pinned-version workflows. Do not install the npm package globally.

Acceptance criteria

• One natural-language latest-update request completes without asking the user to copy/paste npm commands.
• Ordinary $update-wizard repair remains pinned to the active package unless latest was explicitly requested.
• Network/auth failures are reported without partially claiming success.
• Post-update verification reports the applied package and adapter versions.
• CLI and Desktop guidance both require one restart/reopen after successful replacement.
• TDD covers latest, already-current, offline, pinned, and failed-handoff cases.

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Clarified required UX from real Anticheat regression: for customized repositories, the supported default must begin inside a repo-rooted Codex session using the configured frontier High driver. The skill itself should fetch/invoke the newest npm package, preview its deterministic plan, inspect repo-specific contracts (especially AGENTS.md) semantically, preserve or deliberately merge project rules, apply, verify the final diff/check output, and then instruct a restart. Documentation must not send users to run npx codex-sdlc-wizard@latest update outside the AI session as the normal path, because the current command both fetches and mutates and can apply a mistaken manifest classification before semantic review. Keep direct npx as an explicit automation/recovery fallback only after #148 makes it independently preservation-safe.

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E2E acceptance should include Claude Desktop computer-use driving Codex Desktop as a real user on Windows: plugin update/enable -> repo selection -> one natural-language latest-update request -> agent-performed npm handoff -> semantic preservation verification -> full app restart -> exactly one $sdlc -> read-only orientation. The test should fail if users must leave Codex to paste npm commands, if plugin/package/repo-layer versions are ambiguous, or if specialized AGENTS/docs are replaced.