docs(darpa): add formal verification appendix for CLARA proposal (#415)

- Appendix A: Coq proof sketches (Trinity Identity, Ternary Multiplication, VSA Bind Invertibility)
- Appendix A.3: Z3 SMT solver verification (GF16 overflow-freedom, Consciousness monotonicity)
- Appendix A.4: Isabelle/HOL proofs (Sacred Scaling Gradient Amplification)
- Appendix B: Continuous verification pipeline workflow
- Appendix C: High-assurance properties (safety, liveness, security)
- Appendix D: Reproducibility guarantees (bit-exact, cross-platform, temporal)
- Appendix E: Verification deliverables and milestone targets

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

Author: Antigravity Agent