fix(codex): install global plugins through CLI

[corylanou]

Summary

• Register or upgrade the gopher-ai marketplace through the supported Codex CLI and install all six Codex-capable plugins with codex plugin add.
• Delegate plugin enablement and versioned cache publication to Codex while keeping explicit pruning safe for active and incomplete roots.
• Publish synchronized 1.7.2 manifests and update global-install guidance for the public CLI flow.

Test Plan

• Focused installation suite: passed, including first install, reinstall, upgrade, pruning, capability, and legacy cleanup coverage.
• Detent pre-review validation gate: passed for commands, hooks, ship E2E, shared sync, shell, skill metadata, YAML, Go build, and Go tests.
• Diff hygiene, shell syntax, and ShellCheck for touched scripts: passed.

Fixes #253

[chatgpt-codex-connector]

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[chatgpt-codex-connector]

Preserve cache roots when delegating installs

When users re-run --user while a Codex session is still alive, this codex plugin add call is not a no-op even for the same plugin version. I checked the upstream Codex CLI implementation (codex-rs/core-plugins/src/store.rs): PluginStore::install goes through replace_plugin_root_atomically, which replaces the whole plugin cache root when the target version already exists and removes older version directories when installing a new version. That invalidates the absolute hook/skill paths that this installer and docs promise to retain until --prune-cache; the previous implementation explicitly kept complete published roots instead of rewriting them.

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