docs: add DYADIC-DESIGN.md paradigm breakthrough explanation

Created comprehensive documentation explaining Ephapax's revolutionary
dyadic design - the world's first affine/linear dual-mode type system.

DYADIC-DESIGN.md (250+ lines):
- Executive summary of the paradigm breakthrough
- The Strictness Dilemma: why traditional approaches fail
- The Solution: co-equal affine and linear modes
- Formal foundations with Coq theorem statements
- Real-world development workflow (exploration → production)
- Comparison with Rust, Linear Haskell, ATS
- Why this is a breakthrough (eliminates escape hatches)
- Future research directions
- Citation format for academic use

README.md updates:
- Emphasized dyadic design front and center
- "World's first dyadic affine/linear type system"
- Paradigm breakthrough section with detailed explanation
- Enhanced Key Features with dyadic emphasis
- Mode switching examples

This positions Ephapax as a fundamental innovation in type system
design, not just another linear type system.

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

Author: Jonathan D.A. Jewell