refactor: wire design-actions.ts into craftingStore.ts, remove dead code

- Delegates startDesigningEnchantment, cancelDesign, saveDesign, deleteDesign to design-actions.ts
- Passes enchanter level from attunement store to startDesigningEnchantment (fixes hardcoded 0)
- Removes orphaned disenchant-actions.ts (preparation phase handles recovery inline)
- Removes unused imports (CraftingUtils, CraftingDesign, useUIStore)
- Updates regression test to check design-actions.ts instead of craftingStore.ts

docs/project-structure.txt

@@ -293,7 +293,6 @@ Mana-Loop/
 │   │   │   │   ├── crafting-equipment-actions.ts
 │   │   │   │   ├── crafting-material-actions.ts
 │   │   │   │   ├── design-actions.ts
-│   │   │   │   ├── disenchant-actions.ts
 │   │   │   │   ├── equipment-actions.ts
 │   │   │   │   ├── index.ts
 │   │   │   │   └── preparation-actions.ts