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 In doing so, some parts of the codebase have become outdated, unnecessary, or overly-complex as a natural result of this feature prioritization.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

@@ -0,0 +1,28 @@
+import { Controller } from "@hotwired/stimulus";
+
+// Connects to data-controller="sidebar"
+export default class extends Controller {
+  static values = { userId: String };
+  static targets = ["panel", "content"];
+
+  toggle() {
+    this.panelTarget.classList.toggle("w-0");
+    this.panelTarget.classList.toggle("opacity-0");
+    this.panelTarget.classList.toggle("w-[260px]");
+    this.panelTarget.classList.toggle("opacity-100");
+    this.contentTarget.classList.toggle("max-w-4xl");
+    this.contentTarget.classList.toggle("max-w-5xl");
+
+    fetch(`/users/${this.userIdValue}`, {
+      method: "PATCH",
+      headers: {
+        "Content-Type": "application/x-www-form-urlencoded",
+        "X-CSRF-Token": document.querySelector('[name="csrf-token"]').content,
+        Accept: "application/json",
+      },
+      body: new URLSearchParams({
+        "user[show_sidebar]": !this.panelTarget.classList.contains("w-0"),
+      }).toString(),
+    });
+  }
+}