New Design System + Codebase Refresh

[zachgoll]

Since the very first 0.1.0-alpha.1 release, we've been moving quickly to add new features to the Maybe app. In doing so, some parts of the codebase have become outdated, unnecessary, or overly-complex as a natural result of this feature prioritization.

Now that "core" Maybe is complete, we're moving into a second phase of development where we'll be working hard to improve the accuracy of existing features and build additional features on top of "core". This PR is a quick overhaul of the existing codebase aimed to:

• Establish the brand new and simplified dashboard view (pictured above)
• Establish and move towards the conventions introduced in #1788
• Consolidate layouts and improve the performance of layout queries
• Organize the core models of the Maybe domain (i.e. Account::Entry, Account::Transaction, etc.) and break out specific traits of each model into dedicated concerns for better readability
• Remove stale / dead code from codebase
• Remove overly complex code paths in favor of simpler ones