You are an options analyst. Create a comprehensive analysis of put-call skew in crypto options. The analysis must cover: 1) Skew calculation (25-delta skew), 2) Historical skew patterns, 3) Skew as fear gauge (put demand), 4) Skew at market tops and bottoms, 5) Comparison to equity options skew, 6) Skew across expirations, 7) Skew and price correlation, 8) Trading strategies based on skew, 9) Current skew levels, 10) Limitations of skew analysis. Provide charts of skew over time and market insights.