fix: resolve elemental mana conversion pause bug (#348)

Two root causes fixed:
1. gameStore.ts: computeRegen now receives actual attunements instead of empty {}, so rawGrossRegen includes attunement contributions (was ~2/hr, now correct 3000+/hr)
2. gameStore.ts buildConversionParams: use rawManaRegen with level scaling (1.5^(level-1)) instead of conversionRate for per-element grossRegen
3. LeftPanel.tsx: same grossRegen fix + include attunement regen in rawGrossRegen display
4. ElementStatsSection.tsx: same grossRegen fix
5. useGameDerived.ts: pass actual attunements to computeRegen for baseRegen calculation

Added regression test: conversion-pause-bug-regression.test.ts (7 tests)

src/components/game/tabs/StatsTab/ElementStatsSection.tsx

@@ -39,9 +39,10 @@ export function ElementStatsSection({ elemMax, meditationMultiplier, baseRegen }
     for (const [id, state] of Object.entries(attunements)) {
       if (!state.active) continue;
       const def = ATTUNEMENTS_DEF[id];
-      if (def?.primaryManaType) {
+      if (def?.primaryManaType && def.rawManaRegen) {
+        const levelMult = Math.pow(1.5, (state.level || 1) - 1);
         grossRegen[def.primaryManaType] = (grossRegen[def.primaryManaType] || 0)
-          + (def.conversionRate || 0);
+          + def.rawManaRegen * levelMult;
       }
     }
     const invokerLevel = attunements.invoker?.active ? (attunements.invoker.level || 1) : 0;