Remove the Claude skills bridge once Claude Code discovers .agents/skills/

[open-coder-ai]

Chock authors skills into .agents/skills/ (agent-neutral home) and bridges them into .claude/skills/ because Claude Code only discovers the latter. The bridge is copy-based on Windows (symlinks need Developer Mode) and carries an ownership marker so a sync can never delete adopter-authored skills.

When Claude Code learns to discover .agents/skills/ natively, the whole bridge — and its ownership-marker machinery — should be deleted. This issue tracks that upstream capability.