fix(retirement): PR4h journal Δ column

Render the statement points delta (Goal::RetirementStatement#points_delta)
as a signed Δ column after Points — green for a rise, red for a drop,
"—" for the earliest statement per source. This is the point of the
append-only journal (tracking pension-points progression year over
year) and was specced in the design; the value existed in the model but
was never surfaced.

app/views/retirement/show.html.erb

@@ -231,6 +231,7 @@
             <th class="py-2"><%= t("retirement.statements.table.date") %></th>
             <th class="py-2"><%= t("retirement.statements.table.source") %></th>
             <th class="py-2"><%= t("retirement.statements.table.points") %></th>
+            <th class="py-2"><%= t("retirement.statements.table.delta") %></th>
             <th class="py-2"><%= t("retirement.statements.table.amount") %></th>
             <th class="py-2"><%= t("retirement.statements.table.age") %></th>
             <th class="py-2"><%= t("retirement.statements.table.notes") %></th>
@@ -243,6 +244,14 @@
               <td class="py-2 text-primary tabular-nums"><%= I18n.l(statement.received_on) %></td>
               <td class="py-2 text-secondary"><%= statement.pension_source.name %></td>
               <td class="py-2 text-secondary tabular-nums"><%= statement.current_points %></td>
+              <td class="py-2 tabular-nums">
+                <% delta = statement.points_delta %>
+                <% if delta.nil? %>
+                  <span class="text-secondary">&mdash;</span>
+                <% else %>
+                  <span class="<%= delta.negative? ? "text-destructive" : "text-success" %>"><%= format("%+.2f", delta) %></span>
+                <% end %>
+              </td>
               <td class="py-2 text-primary tabular-nums privacy-sensitive"><%= statement.projected_monthly_amount_money&.format %></td>
               <td class="py-2 text-secondary tabular-nums"><%= statement.projected_at_age %></td>
               <td class="py-2 text-secondary"><%= statement.raw_source_doc %></td>

config/locales/views/retirement/de.yml

@@ -109,6 +109,7 @@ de:
         date: Datum
         source: Quelle
         points: Entgeltpunkte
+        delta: Δ
         amount: Projiziert
         age: Mit Alter
         notes: Notizen

config/locales/views/retirement/en.yml

@@ -109,6 +109,7 @@ en:
         date: Date
         source: Source
         points: Points
+        delta: Δ
         amount: Projected
         age: At age
         notes: Notes