Support desktop-owned app-server daemon binaries

[bjdodson-openai]

Summary

• let daemon start and restart persist an explicit absolute --codex-bin path
• preserve --analytics-default-enabled for first-party daemon clients
• keep standalone install and bootstrap behavior unchanged when no override is supplied

Why

Codex Desktop needs a local app-server process that can outlive an app update while Desktop continues to own the bundled CLI lifecycle.

Validation

• just fmt
• just test -p codex-app-server-daemon -p codex-cli (332 passed)
• just fix -p codex-app-server-daemon -p codex-cli
• started, probed, and stopped a detached daemon with a temporary CODEX_HOME and explicit codex binary

[github-actions]

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