Description

Skill loading via workspace symlinks fails for most ACP backends (Codex, Qwen, Goose, Droid, etc.) because AGENT_SKILLS_DIRS only mapped 3 backends (gemini, claude, codebuddy), and the DEFAULT_SKILLS_DIRS fallback (.agents/skills/) is not scanned by any CLI.

Additionally:

• codebuddy was incorrectly mapped to .claude/skills/ instead of .codebuddy/skills/
• Windows symlink type 'dir' requires admin privileges; should use 'junction'
• Backends without native skill directory support (opencode, auggie, copilot, nanobot, qoder) had no fallback mechanism

Context

PR #1246 replaced prompt injection with workspace symlinks for skill loading, but the mapping was incomplete and the generic fallback didn't work. Users reported Codex could not load skills.