Skill Feedback — capture the fuel for skill improvement

Capture and aggregate real-world usage feedback for Agent Skills so the Skill Quality Gate loop can keep improving them over time. Use it whenever a skill misfires or underperforms: a skill triggered wrongly (wrong trigger), failed to auto-load on a relevant request (near-miss / description gap), produced a wrong, broken, or low-quality output (output issue), or the user manually corrected its result (manual correction). Also use it to review accumulated skill feedback before running skill-forge, or to close the feedback loop that raises skill quality. Writes one structured JSON object per line to feedback/<skill>/YYYY-MM-DD.jsonl and can summarize them into a report/expo…