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 In doing so, some parts of the codebase have become outdated, unnecessary, or overly-complex as a natural result of this feature prioritization.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/import/confirms/_mappings.html.erb

@@ -27,7 +27,7 @@
       <p class="justify-self-end"><%= t(".rows_label") %></p>
     </div>
 
-    <div class="border border-alpha-black-25 rounded-md shadow-xs divide-y divide-alpha-black-100 text-sm">
+    <div class="shadow-border-xs rounded-md divide-y divide-alpha-black-100 text-sm">
       <% mappings.sort_by(&:key).each do |mapping| %>
         <div class="px-5 py-3 bg-white first:rounded-tl-xl first:rounded-tr-xl last:rounded-bl-xl last:rounded-br-xl">
           <%= render partial: "import/mappings/form", locals: { mapping: mapping } %>