feat: add preprocessing module for BOM condition transformation

Add M05_PreProcessor module to handle value mapping and condition
simplification for "接头" category before parsing.

Features:
- Value mapping: azxs codes (A0/AT/AH→径向, B0/BT/BZ/BH→下轴向,
  Z0/ZT/ZZ/ZH→中轴向) and lcfw ranges (M01-M11→低压, M12-M16→高压)
- OR condition merging: automatically removes duplicate OR segments
- Smart parentheses handling: removes parentheses for single atoms,
  preserves them when needed for logical structure
- Recursive nested expression processing
- Graceful degradation when "对照表" worksheet is missing

Integration:
- Modified M01_Main to initialize preprocessor after M03_Logic
- Preprocessing applied only for "接头" category
- Updated M99_TestRunner with 8 comprehensive test cases
- All tests passing (50 total: 42 core + 8 preprocessing)

Documentation:
- Added detailed flow documentation for Test_PP_06_FullIntegration
  with mermaid diagrams in docs/Test_PP_06_FullIntegration_流程详解.md
- Updated CLAUDE.md with preprocessing module description and
  documentation guidelines (docs/ vs reference_docs/)

Example transformation:
  Input:  gclj=M16 AND (azxs=A0 OR azxs=AT) AND (lcfw=M01 OR lcfw=M15)
  Output: gclj=M16 AND azxs=径向 AND (lcfw=低压 OR lcfw=高压)

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

CLAUDE.md

@@ -16,6 +16,7 @@ The system follows a modular architecture with clear separation of concerns:
 - **M02_DataIO.bas** - Data input/output operations. Reads source data from "平台配置清单" worksheet and generates categorized output workbooks.
 - **M03_Logic.bas** - Core recursive parser for conditional expressions. Handles logical operators (AND/OR), nested parentheses, and key=value/key!=val conditions. Implements Cartesian products for set operations.
 - **M04_Config.bas** - Column mapping and header priorities. Defines source data columns (CODE, NAME, QTY, CONDITION, CATEGORY) and standard ordering for output.
+- **M05_PreProcessor.bas** - Preprocessing module for condition transformation. Handles value mapping for "接头" category (e.g., azxs=A0→径向, lcfw=M01→低压), duplicate OR condition merging, and nested expression simplification. Uses mapping data from "对照表" worksheet.
 - **M99_TestRunner.bas** - Unit testing framework. Run `RunAllTests()` in VBA Immediate window to execute tests.
 
 ### Class Module
@@ -26,12 +27,37 @@ The system follows a modular architecture with clear separation of concerns:
 
 ```
 Excel "平台配置清单" → M01_Main → M02_DataIO.LoadSourceData() →
-M03_Logic.ParseExpression() → Category Dictionary →
-M02_DataIO.CreateOutputWorkbook() → New Excel Workbook + Error Report
+M05_PreProcessor.PreprocessCondition() → M03_Logic.ParseRule() →
+Category Dictionary → M02_DataIO.CreateOutputWorkbook() →
+New Excel Workbook + Error Report
 ```
 
 ## Key Concepts
 
+### Preprocessing (M05_PreProcessor)
+
+Before parsing conditions, the system applies preprocessing for "接头" (joint) category:
+
+**Value Mapping**:
+- **azxs** (安装形式): Maps codes to descriptive values
+  - A0, AT, AH → 径向
+  - B0, BT, BZ, BH → 下轴向
+  - Z0, ZT, ZZ, ZH → 中轴向
+- **lcfw** (量程范围): Maps range codes to categories
+  - M01-M11 → 低压
+  - M12-M16 → 高压
+
+**OR Condition Merging**:
+- Duplicate OR conditions are automatically merged
+- Example: `azxs=径向 OR azxs=径向` → `azxs=径向`
+- Different values preserve OR structure: `lcfw=低压 OR lcfw=高压`
+
+**Parentheses Handling**:
+- Simplified single-value expressions: `(azxs=A0 OR azxs=AT)` → `azxs=径向`
+- Preserves parentheses when needed: `(lcfw=M01 OR lcfw=M15)` → `(lcfw=低压 OR lcfw=高压)`
+
+Mapping data is loaded from "对照表" worksheet (columns A:B for lcfw, D:E for azxs).
+
 ### Conditional Logic Syntax
 
 Conditions use a specific syntax for product selection:
@@ -78,6 +104,14 @@ This runs unit tests for:
 - OR operations with union operations
 - Nested parentheses handling
 - Logic conflict detection
+- **Preprocessing tests** (Test_PP_01 to Test_PP_08):
+  - azxs mapping load (12 values)
+  - lcfw mapping load (M01-M16)
+  - Value replacement
+  - OR condition merging
+  - Full integration with M03_Logic
+  - Non-"接头" category handling
+  - Unmapped value handling
 
 ### Python Skills (Claude Code Integration)
 
@@ -143,7 +177,9 @@ AutoBOM/
 │   └── ClassModules/     # OOP components (clsErrorLogger)
 ├── .claude/
 │   └── skills/           # Claude Code integration skills
-├── reference_docs/       # Documentation and examples
+├── docs/                 # Code-related documentation
+│   └── Test_PP_06_FullIntegration_流程详解.md
+├── reference_docs/       # Business-related documentation and examples
 └── YTHN-100.xlsm/.xlsx  # Main workbook files
 ```
 
@@ -160,3 +196,46 @@ The system uses `clsErrorLogger` for comprehensive error tracking:
 - **Operator Precedence**: AND is processed before OR, parentheses override default precedence
 - **Recursive Parsing**: Nested expressions are handled recursively in M03_Logic
 - **Dynamic Columns**: Output workbooks detect and include only relevant configuration keys
+
+## Documentation Guidelines
+
+### Document Storage Policy
+
+When creating documentation for this project, follow these guidelines:
+
+**Code-Related Documentation** → Save in `docs/` directory:
+- Technical specifications
+- Algorithm explanations
+- Code flow diagrams
+- Test documentation
+- API/reference documentation for code modules
+- Implementation guides
+
+Examples:
+- `docs/Test_PP_06_FullIntegration_流程详解.md` ✓
+- `docs/M03_Logic_Algorithm.md` ✓
+- `docs/API_Reference.md` ✓
+
+**Business-Related Documentation** → Save in `reference_docs/` directory:
+- Business requirements
+- User manuals
+- Product specifications
+- Industry standards
+- Configuration examples
+- Business process documentation
+
+Examples:
+- `reference_docs/BOM_Requirements.md` ✓
+- `reference_docs/Product_Catalog.xlsx` ✓
+- `reference_docs/User_Guide.pdf` ✓
+
+**Decision Tree**:
+```
+Is it about code implementation or technical details?
+├─ Yes → docs/
+└─ No → Is it about business logic or user-facing content?
+    ├─ Yes → reference_docs/
+    └─ No → Ask for clarification
+```
+
+**Note**: When in doubt, prefer `docs/` for technical content and `reference_docs/` for business content.