Feat: Implement basic web authentication and UI

This commit introduces the foundation for web-based authentication and
user interface. It includes:

- **Session Management**: Securely handling user sessions using
  cryptographically generated tokens, cookies with appropriate security
  flags, and server-side storage.
- **Login/Logout Functionality**: Endpoints for users to log in with
  their credentials and log out, clearing their session.
- **User Interface**: Basic templates for the login page, a list of
  cases, and a detailed view of a single case, allowing users to
  navigate and view their data.
- **Authorization**: An `AuthenticatedWebUser` extractor to ensure only
  logged-in users can access protected web routes.
- **Configuration**: Added a `cookie_secure` option to the configuration
  to control the `Secure` flag on session cookies, useful for local
  development.
- **Dependencies**: Added necessary dependencies for password hashing,
  time handling, and TOML file manipulation.
- **Helper Binary**: Included a `hash-password` binary to simplify
  generating bcrypt hashes for user passwords.

server/users.toml.example

@@ -1,3 +1,8 @@
+# Generate a bcrypt hash for `web_password` e.g. via:
+#   python3 -c "import bcrypt; print(bcrypt.hashpw(b'your-password', bcrypt.gensalt()).decode())"
+# or:
+#   htpasswd -bnBC 12 '' your-password | tr -d ':\n'
+
 [[user]]
 slug = "dr_mueller"
 api_key = "change-me-to-a-secure-key"