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_04-ines.js

@@ -49,7 +49,7 @@ export default withDefaults({
             unit.mem.sentry = null;
             unit.mem.inesSentryAt = null;
             const ax = from.x, ay = from.y, bx = unit.x, by = unit.y;
-            const L2 = (bx - ax) ** 2 + (by - ay) ** 2;
+            const L2 = (bx - ax) * (bx - ax) + (by - ay) * (by - ay);
             const w = num(bb.projectile_range, 1.4);
             const hits = [];
             for (const e of battle.aliveEnemies()) {