补全 UI 设计

- `ItemDescForm` 道具详细信息面板，目前还未添加 DescText 内容的赋值
- `RepoForm` 道具入槽逻辑调整，为了适应 `ItemDescForm` 的点击打开逻辑，点击道具自动匹配槽位改成拖动道具到相应槽位
- 添加了一系列图片素材

Assets/GameMain/Entities/TowerEntity.prefab

@@ -74,7 +74,7 @@ SpriteRenderer:
   m_SortingLayerID: -1805677833
   m_SortingLayer: -1
   m_SortingOrder: 2
-  m_Sprite: {fileID: 7482667652216324306, guid: 75f5f34dc1b5347e0b8351032682f224,
+  m_Sprite: {fileID: 7482667652216324306, guid: 5ba74e3a185274149b15c24b321bead2,
     type: 3}
   m_Color: {r: 1, g: 0.40566027, b: 0.40566027, a: 1}
   m_FlipX: 0
@@ -155,7 +155,6 @@ MonoBehaviour:
   _baseComp: {fileID: 9032148832249544824}
   _scanOrigin: {fileID: 6791423131335728073}
   _retargetInterval: 0.1
-  _autoUpdate: 0
   _attackRangeRenderer: {fileID: 4014432302095443276}
   _attackRangeSegments: 64
   _attackRangeLineWidth: 0.08
@@ -352,7 +351,7 @@ SpriteRenderer:
   m_SortingLayerID: -1805677833
   m_SortingLayer: -1
   m_SortingOrder: 1
-  m_Sprite: {fileID: -2413806693520163455, guid: a86470a33a6bf42c4b3595704624658b,
+  m_Sprite: {fileID: -2413806693520163455, guid: e31321df62f1587469b0733897970679,
     type: 3}
   m_Color: {r: 1, g: 1, b: 1, a: 1}
   m_FlipX: 0
@@ -455,7 +454,7 @@ SpriteRenderer:
   m_SortingLayerID: -1805677833
   m_SortingLayer: -1
   m_SortingOrder: 0
-  m_Sprite: {fileID: 7482667652216324306, guid: 311925a002f4447b3a28927169b83ea6,
+  m_Sprite: {fileID: 7482667652216324306, guid: 80a3790c48fc91d4ebcb4d7e2efbb8c8,
     type: 3}
   m_Color: {r: 0.3584906, g: 0.3584906, b: 0.3584906, a: 1}
   m_FlipX: 0