feat: persist crafting zone selection in sessionStorage (#49)

## Summary

- Applies the same sticky-zone pattern from #48 to the crafting panel (`elysium_craft_zone` key in sessionStorage)
- Introduces a `handleZoneSelect` wrapper so sessionStorage is updated alongside React state on every zone change
- Gracefully falls back to `verdant_vale` if no stored value exists

## Test plan

- [x] Lint — zero errors, zero warnings
- [x] Build — all packages build cleanly
- [ ] Manual: select a non-default zone in the crafting panel, navigate away and back — zone should still be selected
- [ ] Manual: log out and back in — zone should reset to Verdant Vale

✨ This PR was created with help from Hikari~ 🌸

Reviewed-on: #49
Co-authored-by: Hikari <hikari@nhcarrigan.com>
Co-committed-by: Hikari <hikari@nhcarrigan.com>

apps/web/src/components/game/craftingPanel.tsx

@@ -26,7 +26,9 @@ const bonusLabel: Record<string, string> = {
  */
 const CraftingPanel = (): JSX.Element => {
   const { state, craftRecipe, formatNumber } = useGame();
-  const [ activeZoneId, setActiveZoneId ] = useState("verdant_vale");
+  const [ activeZoneId, setActiveZoneId ] = useState(() => {
+    return sessionStorage.getItem("elysium_craft_zone") ?? "verdant_vale";
+  });
   const [ pendingRecipeId, setPendingRecipeId ] = useState<string | null>(null);
 
   if (state === null) {
@@ -68,6 +70,11 @@ const CraftingPanel = (): JSX.Element => {
     });
   }
 
+  function handleZoneSelect(zoneId: string): void {
+    setActiveZoneId(zoneId);
+    sessionStorage.setItem("elysium_craft_zone", zoneId);
+  }
+
   async function handleCraft(recipeId: string): Promise<void> {
     setPendingRecipeId(recipeId);
     try {
@@ -85,7 +92,7 @@ const CraftingPanel = (): JSX.Element => {
 
       <ZoneSelector
         activeZoneId={activeZoneId}
-        onSelectZone={setActiveZoneId}
+        onSelectZone={handleZoneSelect}
         zones={zones}
       />