feat: Complete 2D Visual Overhaul - Isometric to Flat Top-Down

- NEW: Flat2DTerrainSystem.js (375 lines)
- NEW: map2d_data.js procedural map (221 lines)
- MODIFIED: GameScene async create, 2D terrain integration
- MODIFIED: Player.js flat 2D positioning
- MODIFIED: game.js disabled pixelArt for smooth rendering
- FIXED: 15+ bugs (updateCulling, isometric conversions, grid lines)
- ADDED: Phase 28 to TASKS.md
- DOCS: DNEVNIK.md session summary

Result: Working flat 2D game with Stardew Valley style!
Time: 5.5 hours

src/systems/InventorySystem.js

@@ -112,4 +112,13 @@ class InventorySystem {
         }
         return total >= count;
     }
+
+    /**
+     * Alias for addItem() - for simple crafting system compatibility
+     * @param {string} itemKey - Item type/key
+     * @param {number} quantity - Amount to add
+     */
+    addItemToInventory(itemKey, quantity) {
+        return this.addItem(itemKey, quantity);
+    }
 }