Formal Verification of Sidon Set Upper Bounds in Lean 4 with Mathlib: Erdos Problem 30

⚠️ SUPERSEDED — This record (concept DOI 10.5281/zenodo.19324239) has been superseded by the canonical formalization at https://doi.org/10.5281/zenodo.19444427. Please use that record for all citations. This record is retained for archival continuity only. A Lean 4 formalization of the two principal upper bounds for Sidon sets (B2 sets), addressing Erdos Problem 30. 1131 lines of verified Lean 4 code, zero sorry stubs. Proves the Lindstrom bound (1969) and Balogh-Furedi-Roy bound (2023) — current best published upper bound. First formal verification of any Sidon set upper bound beyond the elementary k(k-1) le 2N.