feat(ErdosProblems): Add 114.lean with small-n EHP result (n=3–14)

[bengoechea]

Summary

Adds FormalConjectures/ErdosProblems/114.lean — the Erdős–Herzog–Piranian (EHP) conjecture (#114) with a computationally certified small-n result.

• erdos_114: Full open conjecture (all n)
• erdos_114_small_n: Solved for 3 ≤ n ≤ 14 via IEEE 1788-rigorous interval arithmetic

Context

Moritz Firsching confirmed a standalone PR is welcome:
Zulip message

This PR is intentionally separate from #3422.

Certificates

Each n case is verified independently by branch-and-bound over the compact
parameter space of monic degree-n polynomials, with IEEE 1788-2015 certified
interval arithmetic bounds:

• n = 3–12: Python/mpmath
• n = 13–14: Rust/inari (MPFR-backed)

All results deposited with SHA-256 checksums:
doi:10.5281/zenodo.19480329

Definitions

Name	Description
levelCurveUnit p	Lemniscate {z ∈ ℂ : ‖p(z)‖ = 1}
arcLength p	1-dimensional Hausdorff measure of the level curve

Future work

• Uniqueness theorem (erdos_114_small_n_unique) as a follow-up
• Extension to n = 15+ as compute budget allows

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