Add a comprehensive LegalDocument base class in mywebdav/legal.py with abstract methods for title and content generation, along with full markdown and HTML implementations for compliance statement, contact/complaint mechanism, and cookie policy pages, replacing placeholder content with detailed regulatory and procedural information.
Replace every occurrence of "RBox" with "MyWebdav" in source files, configuration,
legal documents, UI components, and test fixtures. This includes renaming the
`RBoxApp` class to `MyWebdavApp` in the JavaScript component, updating the
TOTP issuer from "RBox" to "MyWebdav" in the auth router, changing the
application description in the argument parser, and updating all user-facing
strings in HTML templates, legal policies, and the manifest file. The
`.env.example` default for `TOTP_ISSUER` is also updated accordingly.
