feat: integrate inventory verification for component materials in BOM extraction

Implement inventory-based component selection logic that accumulates demand
across orders and falls back to sub-components (joint + element) when stock
is insufficient.

**Changes:**
- M04_Config: Add inventory worksheet configuration constants
  - INVENTORY_SHEET_NAME = "现存量"
  - INVENTORY_HEADER_ROW = 3 (headers on row 3)
  - INVENTORY_COL_CODE = "B" (material code)
  - INVENTORY_COL_QTY = "J" (stock quantity)

- M08_ComponentProcessor: Implement inventory tracking and verification
  - Add module-level variables: g_InventoryDict, g_AccumulatedDemandDict
  - Add LoadInventoryData() to load stock from [现存量] worksheet
  - Add InitComponentProcessorWithInventory() for initialization with inventory
  - Rewrite CheckComponentInventory() with actual inventory logic:
    * Calculate cumulative demand = orderQty × bomQty + previousAccumulated
    * Compare with available stock
    * Return True if stock sufficient, False otherwise
    * Update accumulated demand after each order
  - Update ProcessComponentRecord() to accept orderQty parameter

- M09_BOMExtractor: Integrate inventory check into main workflow
  - Modify ReadInputModels() to read 3 columns (orderNo, model, qty)
  - Initialize component processor with inventory support
  - Extract order quantity from column C and pass through call chain
  - Update ProcessSingleModel() and MatchAllMaterialTypesWithValidation()
    signatures to accept orderQty parameter

**Logic Example:**
- 3 orders (PO-001, PO-003, PO-006) use component A
- Each order: quantity=2, BOM qty=1, stock=5
- PO-001: cumulative=2, stock 5>=2 ✓ → return component
- PO-003: cumulative=4, stock 5>=4 ✓ → return component
- PO-006: cumulative=6, stock 5<6 ✗ → return sub-components

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

VBA_BOMConverter/Modules/M04_Config.bas

@@ -67,6 +67,14 @@ Public Const BOMLIB_COL_ELEMENT_NAME As String = "弹性元件名称"
 Public Const BOMLIB_COL_ELEMENT_CODE As String = "弹性元件编码"
 Public Const BOMLIB_COL_ELEMENT_QTY As String = "弹性元件数量"
 
+' ------------------------------------------------------------------------------
+' 现存量工作表配置常量
+' ------------------------------------------------------------------------------
+Public Const INVENTORY_SHEET_NAME As String = "现存量"
+Public Const INVENTORY_HEADER_ROW As Long = 3      ' 表头在第3行
+Public Const INVENTORY_COL_CODE As String = "B"     ' B列 = 物料编码
+Public Const INVENTORY_COL_QTY As String = "J"      ' J列 = 库存数量
+
 ' BOM库条件字段列表（所有可能的条件字段）
 Public Function GetBOMConditionFields() As Variant
     GetBOMConditionFields = Array( _