fix: attunement system spec-vs-code discrepancies (issue #331)

- Fix conversion rate level scaling from linear (1+level*0.5) to exponential (1.5^(level-1)) in conversion-rates.ts
- Fix getAttunementLevelMultiplier formula to match spec §4.3
- Add level-up logging in attunementStore.ts via combat store addActivityLog
- Clarify getAttunementConversionRate returns flat base rate (level scaling applied separately)
- Update spec §8 to describe time-based puzzle room system matching code implementation
- Add 17 regression tests verifying exponential scaling, base rate behavior, and spec table values

src/lib/game/stores/attunementStore.ts

@@ -5,7 +5,8 @@ import { create } from 'zustand';
 import { persist } from 'zustand/middleware';
 import { createSafeStorage } from '../utils/safe-persist';
 import type { AttunementState } from '../types';
-import { getAttunementXPForLevel, MAX_ATTUNEMENT_LEVEL } from '../data/attunements';
+import { getAttunementXPForLevel, MAX_ATTUNEMENT_LEVEL, ATTUNEMENTS_DEF } from '../data/attunements';
+import { useCombatStore } from './combatStore';
 
 export interface AttunementStoreState {
   attunements: Record<string, AttunementState>;
@@ -48,6 +49,19 @@ export const useAttunementStore = create<AttunementStoreState>()(
               break;
             }
           }
+
+          // Log level-up (outside set to avoid nested state updates)
+          if (newLevel > attState.level) {
+            const def = ATTUNEMENTS_DEF[attunementId];
+            const name = def?.name || attunementId;
+            // Use setTimeout to log after state update completes
+            setTimeout(() => {
+              useCombatStore.getState().addActivityLog(
+                'attunement',
+                `${name} reached level ${newLevel}!`
+              );
+            }, 0);
+          }
           
           return {
             attunements: {