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 In doing so, some parts of the codebase have become outdated, unnecessary, or overly-complex as a natural result of this feature prioritization.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

@@ -1,40 +1,20 @@
 class PagesController < ApplicationController
   skip_before_action :authenticate_user!, only: %i[early_access]
-  layout :with_sidebar, except: %i[early_access]
 
   def dashboard
-    @period = Period.from_param(params[:period])
-    snapshot = Current.family.snapshot(@period)
-    @net_worth_series = snapshot[:net_worth_series]
-    @asset_series = snapshot[:asset_series]
-    @liability_series = snapshot[:liability_series]
-
-    snapshot_transactions = Current.family.snapshot_transactions
-    @income_series = snapshot_transactions[:income_series]
-    @spending_series = snapshot_transactions[:spending_series]
-    @savings_rate_series = snapshot_transactions[:savings_rate_series]
-
-    snapshot_account_transactions = Current.family.snapshot_account_transactions
-    @top_spenders = snapshot_account_transactions[:top_spenders]
-    @top_earners = snapshot_account_transactions[:top_earners]
-    @top_savers = snapshot_account_transactions[:top_savers]
-
-    @accounts = Current.family.accounts.active
-    @account_groups = @accounts.by_group(period: @period, currency: Current.family.currency)
-    @transaction_entries = Current.family.entries.incomes_and_expenses.limit(6).reverse_chronological
-
-    # TODO: Placeholders for trendlines
-    placeholder_series_data = 10.times.map do |i|
-      { date: Date.current - i.days, value: Money.new(0, Current.family.currency) }
-    end
-    @investing_series = TimeSeries.new(placeholder_series_data)
+    @period = Period.from_key(params[:period], fallback: true)
+    @balance_sheet = Current.family.balance_sheet
+    @accounts = Current.family.accounts.active.with_attached_logo
   end
 
   def changelog
     @release_notes = Provider::Github.new.fetch_latest_release_notes
+
+    render layout: "settings"
   end
 
   def feedback
+    render layout: "settings"
   end
 
   def early_access