cleanup: 删除kb-workflow遗留代码

- 删除 kb_handler.py，不在SKILL.md要求中
- 删除 kb_pipeline.py，不在SKILL.md要求中
- 修改 bilibili_extractor.py 使用 kb-link-parser 解析短链
- 添加 SkillBug.md 记录问题

Skills should follow their SKILL.md specifications only.

skills/kb-workflow/src/extractors/bilibili_extractor.py

@@ -22,11 +22,13 @@ from bs4 import BeautifulSoup
 
 from .base import Extractor, ExtractionError
 
-# 导入 shortlink_resolver
+# 导入 kb-link-parser 用于短链解析
 import sys
 import os
-sys.path.insert(0, os.path.dirname(os.path.dirname(os.path.dirname(os.path.abspath(__file__)))))
-from shortlink_resolver import ShortLinkResolver
+# 添加 kb-link-parser 到导入路径
+KB_LINK_PARSER_PATH = os.path.dirname(os.path.dirname(os.path.dirname(os.path.dirname(os.path.abspath(__file__)))))
+sys.path.insert(0, os.path.join(KB_LINK_PARSER_PATH, 'kb-link-parser'))
+from link_parser_shortlink import ShortLinkResolver
 from .hard_subtitle_extractor import HardSubtitleExtractor
 
 # 尝试导入 stealth 支持