fix: three bug fixes - library XP scaling, prep time floor, dual design slot logic

Fixes #297: Library room XP now uses 25× rate without undocumented floor multiplier
Fixes #305: Prep time mana-per-tick now applies Math.floor(capacity/50) per spec
Fixes #304: Dual design slot correctly returns false when first slot is empty

src/lib/game/stores/non-combat-room-actions.ts

@@ -127,7 +127,7 @@ function tickLibraryRoom(get: GetFn, set: SetFn, hours: number, advance: Advance
   const required = room.libraryRequired || 1;
 
   const BASE_LIBRARY_XP_PER_HOUR = 50;
-  const xpGrant = Math.floor(BASE_LIBRARY_XP_PER_HOUR * (1 + s.currentFloor / 10) * 25 * hours);
+  const xpGrant = Math.floor(BASE_LIBRARY_XP_PER_HOUR * 25 * hours);
 
   if (xpGrant > 0) {
     const disciplineStore = useDisciplineStore.getState();

src/lib/game/stores/pipelines/enchanting-tick.ts

@@ -84,7 +84,7 @@ export function processEnchantingTicks(
         writes.combat = { ...(writes.combat || {}), currentAction: 'meditate' };
         addLog('Preparation failed: equipment not found.');
       } else {
-        const manaPerTick = (instance.totalCapacity * 10) / (2 + instance.totalCapacity / 50) * HOURS_PER_TICK;
+        const manaPerTick = (instance.totalCapacity * 10) / (2 + Math.floor(instance.totalCapacity / 50)) * HOURS_PER_TICK;
         const prepResult = calculatePreparationTick(
           prepProgress.progress,
           prepProgress.required,