Add Themis application with custom widgets, views, and utilities

- Implemented custom form widgets for date, time, and datetime fields with DaisyUI styling.
- Created utility functions for formatting dates, times, and numbers according to user preferences.
- Developed views for profile settings, API key management, and notifications, including health check endpoints.
- Added URL configurations for Themis tests and main application routes.
- Established test cases for custom widgets to ensure proper functionality and integration.
- Defined project metadata and dependencies in pyproject.toml for package management.

.gitignore

@@ -174,3 +174,7 @@ cython_debug/
 # PyPI configuration file
 .pypirc
 
+# Mnemosyne-specific
+.env.local
+/staticfiles/
+/media/