Anonymous users had two links to assignments in navigation, but none for signing up.

This makes it consistent with the mobile navigation.

Fix dark mode bug where toggling the browser pref would apply the scheme independently of app preference

Teal Bauer authored 3 weeks ago and Teal committed 3 weeks ago

- Improve "My Assignments" style with the new table styles
- Also, bring back Conferences / Assignments
- Change menu layout back to old nav
- Dark mode fixes

Extend admin interface:

- Make admin controllers inherit from Admin::BaseController
- New admin dashboard with system statistics overview
- Centralized admin layout with dedicated navigation
- Enhanced user management interface with role assignment capabilities

RBAC fixes:

- Introduced new `admin` role that has all rights
- Added db migration to create admin role with appropriate permissions
- Updated admin rake tasks for role management
- Updated db seeds to add all required roles properly

Styling improvements and fixes:

- Upgraded button system with standardized styling and dark mode support
- Improved UI with consistent styling using Tailwind components
- Brought back manual dark mode using Tailwind custom variant

This unifies the look of `<h1>`, applies similar spacing across pages
and removes weird styling from templates originating with devise.
Also removes h1 from "logo", because all of our headers start at h1 and
it really isn't a header semantically.

Somewhere h1 and the link were lost.

Includes hamburger menu 

This allows signup, profile edits and login/logout.
Note that due to poor naming, there are conflicts between our session
model und what devise thinks a session should be. In particular, we have
to rename `new_session_path(resource_name)` -> `new_user_session_path`
and `session_path(resource_name)` -> `user_session_path`.

Cf. https://github.com/heartcombo/devise/issues/2800

The state is now fully client-side and handled in session_controller.
This allows us to continue to broadcast the session frame to everyone.