Rank-three real counterexamples to Drury's permanental eigenvalue conjecture with violation ratios approaching e/2

This preprint presents an explicit 214-by-214 integer real positive-semidefinite Gram-matrix counterexample of rank three to Drury’s permanental eigenvalue conjecture, together with exact Python and C++ verification. It also develops an explicit rank-three family whose test-vector violation ratios approach e/2 and derives a bounded theoretical consequence for a real orthogonal interferometer involving three selected output modes. The work is positioned as a follow-on strengthening of the earlier rank-four real counterexample reported by Logan R. Chalmers. It does not claim the first real counterexample, minimum rank, minimum matrix order, optimality of the e/2 limit, or first priority for the three-output optical consequence. The accompanying reproducibility package includes the manuscript, exact witness data, source code, independent verification implementations, build instructions, fresh verification logs, citation metadata, licensing information, and cryptographic checksums. This is a preprint and has not undergone peer review. AI assistance used during research exploration, mathematical derivation, drafting, code generation, testing, verification, and release preparation is disclosed in the accompanying documentation. GitHub repository:https://github.com/gkamal666/drury-rank-three-counterexamples Immutable GitHub release v1.0.0:https://github.com/gkamal666/drury-rank-three-counterexamples/releases/tag/v1.0.0