feat: improve CLI cheatsheet and setup wizard

CLI Cheatsheet:
- Add RouterArena #1 badge and 92% cost savings headline
- Reorganize commands by category (Core/Model/Cost/Memory/Batch)
- Add practical examples with real use cases
- Add proxy usage examples (Python, TypeScript, LangChain)
- Add ensemble mode for hallucination detection
- Add Docker quick reference (container + compose)
- Add benchmark comparison vs OpenRouter
- Add troubleshooting section

Setup Wizard:
- Add tier system (FREE/CHEAP/PAID) with visual icons
- Expand to 30+ provider API key mappings
- Add provider specialties and use-case notes
- Add smart suggestions (free tier first, then cheap)
- Add selection shortcuts: all, free, min
- Add pro tips based on detected keys
- Improve terminal UI with box drawing characters

Author: Das-rebel