Add UI clarity for non-cash account balance tracking (#336)

* Add UI clarity for non-cash account balance tracking

Fixes issue #164 where users were confused that transactions don't
update the balance for "Other Assets" accounts. This is by design -
non-cash accounts (Other Assets, Properties, Vehicles, Loans, Other
Liabilities) are tracked via manual valuations, not transactions.

Changes:
- Add informational alert to Other Assets creation/edit forms
- Add informational alert to account activity page for all non-cash accounts
- Alert explains that balance updates require "New Balance" entries
- Added i18n strings for alerts in English locale files

The alert uses the existing DS::Alert component with info variant to
provide clear, non-intrusive guidance to users about how these account
types work.

* Add spacing to bottom of alert

* Update copy to avoid repetition.

* Another spacing addition

* Leave dead code alone

---------

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

app/views/other_assets/edit.html.erb

@@ -1,6 +1,9 @@
 <%= render DS::Dialog.new do |dialog| %>
   <% dialog.with_header(title: t(".edit", account: @account.name)) %>
   <% dialog.with_body do %>
-    <%= render "form", account: @account, url: other_asset_path(@account) %>
+    <div class="space-y-2">
+      <%= render DS::Alert.new(message: t(".balance_tracking_info"), variant: :info) %>
+      <%= render "form", account: @account, url: other_asset_path(@account) %>
+    </div>
   <% end %>
 <% end %>

app/views/other_assets/new.html.erb

@@ -1,6 +1,9 @@
 <%= render DS::Dialog.new do |dialog| %>
   <% dialog.with_header(title: t(".title")) %>
   <% dialog.with_body do %>
-    <%= render "form", account: @account, url: other_assets_path %>
+    <div class="space-y-2">
+      <%= render DS::Alert.new(message: t(".balance_tracking_info"), variant: :info) %>
+      <%= render "form", account: @account, url: other_assets_path %>
+    </div>
   <% end %>
 <% end %>

config/locales/views/other_assets/en.yml

@@ -3,5 +3,7 @@ en:
   other_assets:
     edit:
       edit: Edit %{account}
+      balance_tracking_info: "Other Assets are tracked via manual valuations using 'New Balance', not transactions. Cashflow will not affect the account balance."
     new:
       title: Enter asset details
+      balance_tracking_info: "Other Assets are tracked via manual valuations using 'New Balance', not transactions. Cashflow will not affect the account balance."