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-kalts2.js

@@ -76,6 +76,7 @@
 import { num, talentBb, skillRec, batMod, up } from '../shared/tier1.js';
 import { releaseSkillSummon } from '../../tokens.js';
 import { COLS } from '../../../constants.js';
+import { hypot } from '../../../detmath.js';
 
 const S1 = 'skchr_kalts2_1';
 const S2 = 'skchr_kalts2_2';
@@ -235,7 +236,7 @@ function startTransport(battle, unit, anchor) {
     }, { owner: unit });
   }
   const from = { x: unit.x, y: unit.y }, to = { x: anchor.x, y: anchor.y };
-  const T = Math.hypot(to.x - from.x, to.y - from.y) / TRANSPORT_SPEED;
+  const T = hypot(to.x - from.x, to.y - from.y) / TRANSPORT_SPEED;
   const f = { t0: battle.time, T, from, to, hit: new Set(), anchor, r: anchor.tileR, c: anchor.tileC, dir: anchor.dir };
   unit.mem.k2flight = f;
   battle.releaseBlocked(unit);