v0.7.0 — Agent-agnostic skill stamping

The Atelier operator skill is now discoverable by Claude Code, Codex, and PI — not just Claude Code — and stays out of the ADW coding agents the engine spawns.

Highlights

• Canonical .agents/skills/ — the stamp materializes the operator skill at the vendor-neutral .agents/skills/atelier/ (read natively by Codex) and symlinks each skill entry into .claude/skills/<skill> and .pi/skills/<skill>. Per-entry, so the links sit alongside whatever skills a target already keeps there, link only entries that exist (no dangling links), and never clobber a name already taken.
• update.py migration + self-heal — repos stamped before this release (skill at .claude/skills) migrate automatically: old files removed, empty dirs pruned, per-entry symlinks re-established.
• pi isolation — agent_pi.py now passes --no-skills, so ADW pi coding agents no longer inhale the stamped operator skill (or the operator's personal ~/.pi/agent/skills), matching the isolation agent_cc.py already had via setting_sources: [].

Validation

• just test green: 192 engine pytest + 76 cockpit vitest + both seam-parity checks.
• Live smoke with the real CLIs: codex and pi both discover the stamped atelier; install + update/migration verified end-to-end (including coexistence with a target's own .claude/skills); pi isolation confirmed via A/B (without --no-skills pi pulls in 20+ ambient user skills, with it, none).

Full PR: #42