Skip unnecessary sync when account balance unchanged on update (#1040)

The update action was calling set_current_balance (which triggers
sync_later internally) on every form submission, even when the balance
hadn't changed. This caused the account to enter a syncing state,
replacing the visible balance with a pulsing skeleton placeholder
until the sync completed.

Now we compare the submitted balance against the current value and
only call set_current_balance when it actually differs. Also removes
a redundant sync_later call that duplicated the one already inside
set_current_balance.

Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>

app/controllers/concerns/accountable_resource.rb

@@ -41,15 +41,14 @@ module AccountableResource
   end
 
   def update
-    # Handle balance update if provided
-    if account_params[:balance].present?
+    # Handle balance update if the value actually changed
+    if account_params[:balance].present? && account_params[:balance].to_d != @account.balance
       result = @account.set_current_balance(account_params[:balance].to_d)
       unless result.success?
         @error_message = result.error_message
         render :edit, status: :unprocessable_entity
         return
       end
-      @account.sync_later
     end
 
     # Update remaining account attributes