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-ray.js

@@ -63,6 +63,7 @@ import { sortEnemyTargets } from '../../../targeting.js';
 import { bodyInKeys } from '../../../body.js';
 import { PUSH_DIRECTIONAL_MIN_DIST } from '../../../constants.js';
 import { startCountdown } from '../../tokens.js';
+import { hypot } from '../../../detmath.js';
 
 const S1 = 'skchr_ray_1';
 const S2 = 'skchr_ray_2';
@@ -159,7 +160,7 @@ export default {
               if (!target.alive) { unit.mem.rayLoadExtra = num(unit.mem.rayLoadExtra) + Math.max(0, Math.floor(num(b1.cnt, 1))); return; }
               const force = num(b1.force, 1);
               const [fr, fc] = unit.fwd;
-              const vx = target.x - unit.x, vy = target.y - unit.y, d = Math.hypot(vx, vy);
+              const vx = target.x - unit.x, vy = target.y - unit.y, d = hypot(vx, vy);
               if (d >= PUSH_DIRECTIONAL_MIN_DIST && vx * fc + vy * fr >= d * Math.SQRT1_2) battle.push(target, force, { from: unit, dir: { x: fc, y: fr }, fixed: true });
               else battle.push(target, force - 1, { from: unit });
             },