feat: revamp website — tabbed commands, comparison table, plugin showcase, terminal demo

- New 8-step animated terminal demo (/review → /provider → /commit)
- Tabbed command showcase with 32 commands across 7 categories
- Plugin system section with syntax-highlighted code example
- 12-row comparison table vs Claude Code and Codex CLI
- "Quick start" 4-step grid replacing How it works
- 9 feature cards (6 marked NEW) with hover animations
- Provider cards with Ollama highlighted as free/local
- Updated stats: 30+ commands, 4 providers, MIT

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: thegreatalxx