feedback7: the battle sim uses engine-independent math — Chrome, Firefox, Safari and the server agree bit for bit (PR #373 by @Cloudnyco)

- server/sim/detmath.js: hypot (sqrt of the squares, rescaled outside 2^±500), powi (integer powers in double-double,
  one rounding), sin / cos (fdlibm 5.3) and atan2 (fdlibm / FreeBSD msun) built only from correctly rounded IEEE
  operations; the sim's Math.hypot / sin / cos / atan2 / pow calls go through it (65 files); eslint.config.js forbids
  the approximated Math functions under server/sim and test/sim/detmath.test.js scans for them.
- sin / cos / atan2 are the algorithms V8 runs in Node, so the server's results stay; only hypot differs from V8's.
  Golden: 2 moved — diy-027 (a hypot distance, damage +80) and coop3-ABYSS-5 (a later card pick from round 9, same end).
- Applied unchanged after review (Grok static review: MERGE; the diff read in full: no network, no new dependency).
- Tests: broad node --test 5155 / 5155 with the new file tracked (detmath 7 / 7, package 10 / 10); lint 0 errors,
  typecheck, check:imports.

server/sim/content/kits/ops/op-veen.js

@@ -42,6 +42,7 @@
 
 import { num, talentBb, moduleBb, traitBb, skillRec, batMod, toggleBuff } from '../shared/tier1.js';
 import { canTargetEnemy, sortEnemyTargets } from '../../../targeting.js';
+import { hypot } from '../../../detmath.js';
 
 const S1 = 'skchr_veen_1';
 const S2 = 'skchr_veen_2';
@@ -115,7 +116,7 @@ export default {
           if (!pool.length) pool = near;
           let next = null, bd = Infinity;
           for (const e of pool) {
-            const d = Math.hypot(e.x - cur.x, e.y - cur.y);
+            const d = hypot(e.x - cur.x, e.y - cur.y);
             if (d < bd - 1e-9 || (Math.abs(d - bd) <= 1e-9 && next && e.spawnSeq < next.spawnSeq)) { bd = d; next = e; }
           }
           if (!next) return;   // nobody within reach: the bounces left are lost