chore: 忽略 Office 文档与虚拟环境目录

手续费.xlsx 一类文件放在仓库旁但不属于仓库；~$ 开头的是 Excel 打开工作簿
时生成的锁文件，每次都会重新出现并占据 git status。

.venv 一并声明：venv 自 3.11 起会在它创建的目录内写 .gitignore，但仅覆盖
该目录，换个位置或用旧版本就失效。

Co-authored-by: Cursor <cursoragent@cursor.com>

.gitignore

@@ -15,8 +15,19 @@ __pycache__/
 *.sqlite-shm
 *.sqlite-wal
 
+# Office documents kept alongside the repo but not part of it.
+# "~$" files are Excel's lock files, recreated every time a workbook is opened.
+*.xlsx
+*.xls
+~$*
+
 # Local data
 data/
 
+# Virtualenvs. venv writes its own .gitignore since 3.11, but only for the
+# directory it creates — declare it here so other layouts are covered too.
+.venv/
+venv/
+
 # Local tooling
 .gstack/