New Design System + Codebase Refresh (#1823)

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 In doing so, some parts of the codebase have become outdated, unnecessary, or overly-complex as a natural result of this feature prioritization.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 Cursor rules and project design overview #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

app/views/layouts/shared/_footer.html.erb

@@ -0,0 +1,6 @@
+<footer class="p-6">
+  <div class="space-y-2 text-center text-xs text-secondary">
+    <p>&copy; <%= Date.current.year %>, Maybe Finance, Inc.</p>
+    <p><%= link_to t(".privacy_policy"), "https://maybefinance.com/privacy", class: "underline hover:text-gray-600" %> &bull; <%= link_to t(".terms_of_service"), "https://maybefinance.com/tos", class: "underline hover:text-gray-600" %></p>
+  </div>
+</footer>