docs: rewrite README as manifesto for viral launch

Transform from technical documentation to brand storytelling:
- Hook: "Your AI Agent Just Tried to rm -rf /. We Stopped It."
- ASCII hero shot showing AIRLOCK_BLOCK in action
- Villain narrative positioning against $50K enterprise vendors
- Origin story establishing authenticity
- Bold claims backed by code (70% cost reduction)
- Prominent comparison table with competitors
- The Numbers section (182 tests, 84% coverage)

Author: sattyamj-attri