Add 20 new thinking skills and quality improvement scripts

New thinking skills added:
- thinking-leverage-points: Donella Meadows' intervention hierarchy
- thinking-five-whys-plus: Enhanced root cause analysis with bias guards
- thinking-fermi-estimation: Order-of-magnitude calculations
- thinking-opportunity-cost: Evaluate choices by what you give up
- thinking-probabilistic: Calibrated probability estimation (superforecasting)
- thinking-reversibility: Bezos' Type 1/Type 2 decision framework
- thinking-regret-minimization: Project to 80-year-old self
- thinking-via-negativa: Taleb's improvement by subtraction
- thinking-lindy-effect: Future life proportional to current age
- thinking-margin-of-safety: Build in buffers for uncertainty
- thinking-thought-experiment: Structured imagination
- thinking-steel-manning: Argue strongest opposing position
- thinking-jobs-to-be-done: Christensen's JTBD framework
- thinking-effectuation: Sarasvathy's entrepreneurial reasoning
- thinking-cynefin: Snowden's complexity domains
- thinking-theory-of-constraints: Goldratt's bottleneck management
- thinking-scientific-method: Hypothesis-driven investigation
- thinking-red-team: Adversarial self-attack
- thinking-model-selection: Choose the right model for the problem
- thinking-model-combination: Combine multiple models for richer analysis

Quality improvement scripts added:
- scripts/validate-skills.js: Check skills against quality criteria
- scripts/enhance-skill.js: Generate specific improvement suggestions
- scripts/generate-improvement-prompt.js: Create AI prompts for skill enhancement
- scripts/QUALITY_FRAMEWORK.md: Documentation of quality standards

Total skills: 38 (18 original + 20 new)

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>