Create Public Authority account type

As a Public Authority I want to be able to
- log in the app
- add/edit/delete updates (logs should be kept and made visible for all users to prevent misleading information)
- edit my public authority profile
- view stats about the usage of the app (how many people/hood)
- delete my account

No files, tests, or entry points are named. Start by surveying the repository's existing account, authentication, update, profile, and statistics flows, then clarify the Public Authority data model and permissions with maintainers. Done would require all listed capabilities, visible update logs, usage statistics, and account deletion.

Written by the indexing model from the issue text.