fix: resolve priority 4 issues — discipline mutation, skill→discipline migration, uiStore persistence, game loop interval, toast listener leak, page re-renders

- Issue 70: Fix discipline-slice.ts nested element mutation (use immutable spread)
- Issue 71: Add persist middleware to uiStore for paused/gameOver/victory
- Issue 72: Wire discipline effects into calcDamage (spell-casting, void-manipulation)
- Issue 73: Fix useGameLoop interval recreation (use getState() + empty deps)
- Issue 74: Fix use-toast.ts listener leak (change [state] dep to [])
- Issue 75: Reduce page.tsx re-renders with useShallow for multi-field subscriptions
- Issue 76: Fix createGatherMana hardcoded click mana (use computeClickMana with discipline effects)
- Issue 77: Pass discipline effects to computeMaxMana/computeRegen/calcInsight in tick()
- Export DisciplineBonuses type and useDisciplineStore from barrel exports
- Update tests to match new function signatures

src/lib/game/stores/index.ts

@@ -20,6 +20,8 @@ export type { CraftingState, CraftingActions } from './craftingStore';
 export { useAttunementStore } from './attunementStore';
 export type { AttunementStoreState } from './attunementStore';
 
+export { useDisciplineStore } from './discipline-slice';
+
 export { useGameStore } from './gameStore';
 export { useGameLoop } from './gameHooks';
 export type { GameCoordinatorState, GameCoordinatorStore } from './gameStore';