refactor: 工程清理，打造基础模板

- 删除冗余文件：main_backup/main_minimal/main_full、GD32F4xx_AddOn_Temp/、GD32F4xx_Custom_Backup/、GD32F4xx_Official/
- 删除无关工具：read_pdf.py、openocd_test.txt、version.txt
- 重构 main.cpp：去除 STEP 机制，简化为线性启动流程
- 清理 CMakeLists.txt：移除 usart0.c 引用、死代码、冗余 REMOVE_ITEM
- 修正 config.h SystemCoreClock 为 168MHz
- 修复 gd32f4xx_it.cpp 中已删除的 main.h 引用

tools/openocd_test.txt

@@ -1,2 +0,0 @@
-Error: Debug Adapter has to be specified, see "adapter driver" command
-

tools/read_pdf.py

@@ -1,20 +0,0 @@
-# -*- coding: utf-8 -*-
-import sys
-import PyPDF2
-
-def extract_pdf_text(pdf_path):
-    try:
-        with open(pdf_path, 'rb') as file:
-            pdf_reader = PyPDF2.PdfReader(file)
-            text = ""
-            for page_num in range(len(pdf_reader.pages)):
-                page = pdf_reader.pages[page_num]
-                text += page.extract_text()
-            return text
-    except Exception as e:
-        return f"Error reading PDF: {e}"
-
-if __name__ == "__main__":
-    pdf_path = "ÁºÉ½Pi¿ª·¢°å.pdf"
-    text = extract_pdf_text(pdf_path)
-    print(text[:2000])

tools/read_pdf2.py

@@ -1,48 +0,0 @@
-# -*- coding: utf-8 -*-
-import sys
-import os
-
-# 尝试用简单方法读取PDF
-pdf_path = "LSPi_Project/doc/梁山Pi开发板.pdf"
-
-# 方法1: 尝试使用pdfminer（如果可用）
-try:
-    from pdfminer.high_level import extract_text
-    text = extract_text(pdf_path)
-    print("=== PDF内容 (pdfminer) ===")
-    print(text[:3000])
-    sys.exit(0)
-except ImportError:
-    print("pdfminer不可用")
-
-# 方法2: 尝试用二进制读取并查找可打印字符
-try:
-    with open(pdf_path, 'rb') as f:
-        data = f.read()
-    
-    # 提取可打印ASCII字符
-    text_chars = []
-    for byte in data:
-        if 32 <= byte < 127:  # 可打印ASCII
-            text_chars.append(chr(byte))
-        elif byte == 10 or byte == 13:  # 换行符
-            text_chars.append('\n')
-    
-    text = ''.join(text_chars)
-    
-    # 查找可能有用的部分
-    lines = text.split('\n')
-    useful_lines = []
-    keywords = ['pin', 'gpio', 'uart', 'i2c', 'spi', 'adc', 'timer', 'usart', 'tx', 'rx', 'scl', 'sda', 'miso', 'mosi', 'sck', 'cs']
-    
-    for line in lines:
-        line_lower = line.lower()
-        if any(keyword in line_lower for keyword in keywords):
-            useful_lines.append(line)
-    
-    print("=== 提取的有用信息 ===")
-    for line in useful_lines[:50]:
-        print(line)
-        
-except Exception as e:
-    print(f"错误: {e}")

tools/read_pdf_simple.py

@@ -1,43 +0,0 @@
-#!/usr/bin/env python3
-import sys
-import os
-
-pdf_path = "LSPi_Project/doc/ÁºÉ½Pi¿ª·¢°å.pdf"
-
-# Simple binary read and extract text
-try:
-    with open(pdf_path, 'rb') as f:
-        data = f.read()
-    
-    # Extract printable ASCII characters
-    text_chars = []
-    for byte in data:
-        if 32 <= byte < 127:  # Printable ASCII
-            text_chars.append(chr(byte))
-        elif byte == 10 or byte == 13:  # Newline
-            text_chars.append('\n')
-    
-    text = ''.join(text_chars)
-    
-    # Find potentially useful sections
-    lines = text.split('\n')
-    useful_lines = []
-    keywords = ['pin', 'gpio', 'uart', 'i2c', 'spi', 'adc', 'timer', 'usart', 'tx', 'rx', 'scl', 'sda', 'miso', 'mosi', 'sck', 'cs', 'pa', 'pb', 'pc', 'pd', 'pe', 'pf', 'pg']
-    
-    for line in lines:
-        line_lower = line.lower()
-        if any(keyword in line_lower for keyword in keywords):
-            useful_lines.append(line)
-    
-    print("=== Useful information from PDF ===")
-    for i, line in enumerate(useful_lines[:100]):
-        print(f"{i+1}: {line}")
-        
-    # Also show some general content
-    print("\n=== First 2000 characters of PDF content ===")
-    print(text[:2000])
-        
-except Exception as e:
-    print(f"Error: {e}")
-    import traceback
-    traceback.print_exc()