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/chess_char_4_05-beewax.js

@@ -5,6 +5,7 @@ import { COLS } from '../../../constants.js';
 import {
   num, tbb, grid, targetsInRange, targetsInGrid, toggleBuff, skillActive, withDefaults,
 } from '../shared/tier4.js';
+import { hypot } from '../../../detmath.js';
 
 /**
  * Free tile for a summon/device: in the rect, standable, not reserved (Battle.isReservedTile: empty, no knocked-out
@@ -39,7 +40,7 @@ export default withDefaults({
           for (const k of unit.rangeKeys || []) {
             const r = (k / COLS) | 0, c = k % COLS;
             if (!freeTile(battle, r, c)) continue;
-            const d = Math.hypot(c - ref.x, r - ref.y) + (battle.grid.groundPassable(r, c) ? 0 : 5);
+            const d = hypot(c - ref.x, r - ref.y) + (battle.grid.groundPassable(r, c) ? 0 : 5);
             if (d < bd - 1e-9) { bd = d; best = [r, c]; }
           }
           if (!best) return;