feat(hybrid-v2): L2 cosine similarity + golden tests N=5..152

[gHashTag]

Summary

• Add --hybrid-v2, --n <N>, --theta flags to tri math compare
• L2 cosine similarity between phi^k and Pell P_{k+1} vectors in R^N
• f64 Pell numbers to avoid u64 overflow at N>60
• Golden tests for N={5,10,15,20,50,152} — all pass
• 10 Rust unit tests for golden values + convergence + plateau detection
• Update hybrid-conjecture.md with frozen definitions and golden values

Key results

N	cos(theta)	theta (deg)
5	0.964916	15.22
10	0.961774	15.89
15	0.961744	15.90
20	0.961744	15.90
50	0.961744	15.90
152	0.961744	15.90

Plateau reached at N=15, stable to 10+ digits by N=20.

Closes #339 Closes #287

Constitutional compliance

• L1: Closes feat(cli): hybrid v2 golden tests N=5..152 #339, feat(math): hybrid v2 — L2 cosine, dimension N, reproducible convergence (Trinity × Pellis) #287
• L3: ASCII-only, English identifiers
• L4: 10 Rust unit tests for golden values
• L7: no new shell scripts

[github-actions]

📓 NotebookLM Notebook linked to this PR

• Notebook ID: b83263109fb055dc
• URL: https://notebooklm.google.com/notebook/b83263109fb055dc

This notebook contains session context, decisions, and artifacts for this work.