Update documentation after refactoring: AGENTS.md, GAME_BRIEFING.md, skills.md

- Updated AGENTS.md to include store/ directory and clarify store architecture
- Updated GAME_BRIEFING.md Code Architecture section with store/ and legacy store info
- Updated skills.md with skill state management information
- Includes other refactoring changes (store hooks, component updates, etc.)

AGENTS.md

@@ -166,6 +166,13 @@ src/
     │   │   ├── gameLoopActions.ts    # Game loop logic
     │   │   ├── gameActions.ts        # Generic game actions
     │   │   └── gameHooks.ts          # Store hooks
+    │   ├── store/                    # Legacy store slices (migration in progress)
+    │   │   ├── index.ts             # Re-exports from store.ts + computed utils
+    │   │   ├── combatSlice.ts       # Combat state slice
+    │   │   ├── manaSlice.ts         # Mana state slice
+    │   │   ├── skillSlice.ts        # Skill state slice
+    │   │   ├── craftingSlice.ts     # Crafting state slice
+    │   │   └── computed.ts          # Computed stats
     │   ├── store-modules/             # Legacy store utilities
     │   ├── crafting-actions/          # Modular crafting system (NEW)
     │   │   ├── index.ts