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 In doing so, some parts of the codebase have become outdated, unnecessary, or overly-complex as a natural result of this feature prioritization.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/javascript/controllers/bulk_select_controller.js

@@ -146,7 +146,9 @@ export default class extends Controller {
 
   _updateGroups() {
     this.groupTargets.forEach((group) => {
-      const rows = this.rowTargets.filter((row) => group.contains(row));
+      const rows = this.rowTargets.filter(
+        (row) => group.contains(row) && !row.disabled,
+      );
       const groupSelected =
         rows.length > 0 &&
         rows.every((row) => this.selectedIdsValue.includes(row.dataset.id));