Improve or verify the best-known [60,30] linear code over GF(4): current bounds 17 ≤ d ≤ 23

A linear $[n,k]_q$ code is a $k$-dimensional subspace of $\mathbb{F}_{4}^n$; its minimum distance $d$ is the smallest Hamming weight of a nonzero codeword. For $[n,k]=[60,30]$ over $\mathbb{F}_{4}$ the largest achievable minimum distance is unknown: the best-known code has $d=17$ and the best nonexistence (upper) bound is $23$, i.e. $17 \le d_{\max}(60,30) \le 23$. The lower bound is met by an explicit best-known code (constructed from an extended quadratic-residue code by puncturing and shortening); the upper bound is a nonexistence bound. Question: construct a linear $[60,30]_{4}$ code with minimum distance $\ge 18$ (a new record, improving the lower bound), or independently verify that the recorded best-known $[60,30,17]_{4}$ code has minimum distance exactly $17$.

Acceptance. FULLY RESOLVES (improve): a generator matrix $G\in\mathbb{F}_{4}^{30\times60}$ with $\mathrm{rank}(G)=30$ whose minimum distance $d'\ge 18$, certified by a minimum-distance computation (e.g. Brouwer–Zimmermann in Magma/GAP/SageMath); $d'=23$ would settle the cell. PARTIAL: independently recompute, with a re-runnable script, the minimum distance of the recorded best-known $[60,30,17]_{4}$ code from its generator matrix and confirm it equals $17$ (reproduction of the record). Provide $G$ and the verification code.