docs: reorganize LSD skill documentation structure

[nipsysdev]

Restructures LSD skill documentation for improved usability:

• Reduces reference documentation by 70-90% while preserving core principles
• Adds examples/complex-application.md with comprehensive real-world examples (1,612 lines)
• Reorganizes references into actionable quick-reference tables
• Adds dedicated theme-variables.md for theming guidance
• Simplifies SKILL.md with clear workflows and quality checklist
• Separates concerns between specs, patterns, and examples

Changes:

• SKILL.md: 240 → 152 lines (streamlined workflow)
• Reference docs condensed to essential patterns + critical rules
• New component-catalog.md (quick lookup of 39 components)
• New component-patterns.md (practical usage patterns)

Fixes component count (39 vs 41) and corrects ButtonGroupButton → Button usage.