Agent Skills: learn-from-session

Extract durable lessons from a completed Claude session and codify them in the right CLAUDE.md files or skills. Use at the end of a long session, after a bug hunt that surfaced a non-obvious constraint, or when the user asks "what can we learn from this session". Discovers CLAUDE.md files dynamically, routes lessons by generic scope (project / shared conventions / environment / machine-local), enforces neutral voice, and asks for approval before editing.