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-aglna2.js

@@ -63,6 +63,7 @@ import { bodyInKeys } from '../../../body.js';
 import { hasHp } from '../../../damage.js';
 import { RESIST_STATUSES } from '../../../buffs.js';
 import { TICK } from '../../../constants.js';
+import { hypot } from '../../../detmath.js';
 
 const S1 = 'skchr_aglna2_1';
 const S2 = 'skchr_aglna2_2';
@@ -342,7 +343,7 @@ export default {
           if (!st || !skillOn(unit, S3) || !up(unit) || st.flight || !unit.canAct || unit.blocking.length) return;
           const tgt = moveTarget(battle, unit);
           if (!tgt) return;
-          const dur = Math.hypot(tgt.r - unit.tileR, tgt.c - unit.tileC) / MOVE_SPEED;
+          const dur = hypot(tgt.r - unit.tileR, tgt.c - unit.tileC) / MOVE_SPEED;
           const act = unit.skill.activations;
           st.flight = tgt;
           battle.releaseBlocked(unit);