Balance sheet cache layer, non-blocking sync UI (#2356)

* Balance sheet cache layer with cache-busting

* Update family cache timestamps during Sync

* Less blocking sync loaders

* Consolidate family data caching key logic

* Fix turbo stream broadcasts

* Remove dev delay

* Add back account group sorting

app/models/balance_sheet/classification_group.rb

@@ -0,0 +1,61 @@
+class BalanceSheet::ClassificationGroup
+  include Monetizable
+
+  monetize :total, as: :total_money
+
+  attr_reader :classification, :currency
+
+  def initialize(classification:, currency:, accounts:)
+    @classification = normalize_classification!(classification)
+    @name = name
+    @currency = currency
+    @accounts = accounts
+  end
+
+  def name
+    classification.titleize.pluralize
+  end
+
+  def icon
+    classification == "asset" ? "plus" : "minus"
+  end
+
+  def total
+    accounts.sum(&:converted_balance)
+  end
+
+  def syncing?
+    accounts.any?(&:syncing?)
+  end
+
+  # For now, we group by accountable type. This can be extended in the future to support arbitrary user groupings.
+  def account_groups
+    groups = accounts.group_by(&:accountable_type)
+                     .transform_keys { |at| Accountable.from_type(at) }
+                     .map do |accountable, account_rows|
+                       BalanceSheet::AccountGroup.new(
+                         name: accountable.display_name,
+                         color: accountable.color,
+                         accountable_type: accountable,
+                         accounts: account_rows,
+                         classification_group: self
+                       )
+                     end
+
+    # Sort the groups using the manual order defined by Accountable::TYPES so that
+    # the UI displays account groups in a predictable, domain-specific sequence.
+    groups.sort_by do |group|
+      manual_order = Accountable::TYPES
+      type_name    = group.key.camelize
+      manual_order.index(type_name) || Float::INFINITY
+    end
+  end
+
+  private
+    attr_reader :accounts
+
+    def normalize_classification!(classification)
+      raise ArgumentError, "Invalid classification: #{classification}" unless %w[asset liability].include?(classification)
+      classification
+    end
+end