refactor: split bloated state types into State + Actions interfaces (issue #102)

- CombatState: split into CombatState (data) + CombatActions + CombatStore
- PrestigeState: split into PrestigeState (data) + PrestigeActions + PrestigeStore
- ManaState: split into ManaState (data) + ManaActions + ManaStore
- GameState: deprecated, removed from barrel exports
- crafting-actions: updated to use CraftingState instead of GameState
- combat-utils/mana-utils: replaced Pick<GameState,...> with focused interfaces
- DisciplineCardProps: split into Definition + Runtime + Callbacks
- stores/index.ts: now exports both State and Actions types

src/lib/game/stores/gameActions.ts

@@ -39,7 +39,7 @@ export const createGatherMana = () => () => {
 
   // Compute click mana with discipline bonuses (mana-channeling → clickManaMultiplier)
   const cm = computeClickMana(
-    { skills: {} },
+    {},
     disciplineEffects,
   );