The Codex adapter was the only one injecting skills into
<cwd>/.agents/skills/, polluting the project's git repo. All other
adapters (Gemini, Cursor, etc.) use a home-based directory. This
changes the Codex adapter to inject into ~/.codex/skills/ (resolved
via resolveSharedCodexHomeDir) to match the established pattern.
Co-Authored-By: Paperclip <noreply@paperclip.ing>