Refactor password handling and model typing

Replaced custom password generation and verification logic with a new pkg/password.py module using Argon2 for secure hashing. Updated model field types to use PEP 604 union syntax (e.g., str | None) and improved type annotations. Refactored admin and session routes to use new password utilities and direct model methods for CRUD operations. Removed legacy tool-based password functions and cleaned up .idea project files.

.idea/.gitignore

@@ -1,8 +0,0 @@
-# 默认忽略的文件
-/shelf/
-/workspace.xml
-# 基于编辑器的 HTTP 客户端请求
-/httpRequests/
-# Datasource local storage ignored files
-/dataSources/
-/dataSources.local.xml