fix: resolve Python anti-patterns and remove duplicate rrf entry

[Jah-yee]

Good day,

Summary

I found and fixed the remaining Python anti-patterns in the codebase that were not addressed in previous PRs.

Changes

1. Replace == None with is None (3 instances)

• src/biz_layer/mem_memorize.py (lines 1293, 1329, 1348)
• Following PEP 8: use is None or is not None instead of == None or != None

2. Replace bare except with except Exception (2 instances)

• src/biz_layer/mem_db_operations.py (line 146)
• src/infra_layer/adapters/out/search/repository/episodic_memory_milvus_repository.py (line 127)
• Bare except clauses catch all exceptions including SystemExit and KeyboardInterrupt

3. Remove duplicate rrf entry in docstring

• demo/utils/simple_memory_manager.py (line 251)
• Clarified the remaining rrf description as Keyword + Vector + Reciprocal Rank Fusion

Testing

• Python syntax validation passed (python3 -m py_compile)
• All modified files compile without errors

Related Issues

• Related to fix: resolve typos, replace == None/!= True with is None/is not True, replace bare except #126, fix: replace == None/!= True with is None/is not True (Python anti-pa… #113, fix: replace bare except with except Exception #107 which address similar issues in other parts of the codebase

感谢你们的奉献，希望能提供帮助。如果我解决得有问题或有待商妥的地方，请在下面留言，我会来处理。

Warmly,
Taizi