Add a new field to the alert schema to fix a mismatch between the prior schema and the upstream NWS API

internal/sinks/postgres/map_test.go

@@ -103,6 +103,8 @@ func TestMapPostgresEventForecastStructPayload(t *testing.T) {
 
 func TestMapPostgresEventAlertStructPayload(t *testing.T) {
 	sent := time.Date(2026, 3, 16, 17, 0, 0, 0, time.UTC)
+	ends := time.Date(2026, 3, 16, 20, 0, 0, 0, time.UTC)
+	expires := time.Date(2026, 3, 16, 18, 30, 0, 0, time.UTC)
 	run := model.WeatherAlertRun{
 		AsOf: time.Date(2026, 3, 16, 18, 0, 0, 0, time.UTC),
 		Alerts: []model.WeatherAlert{
@@ -110,6 +112,8 @@ func TestMapPostgresEventAlertStructPayload(t *testing.T) {
 				ID:       "urn:alert:1",
 				Headline: "Winter Weather Advisory",
 				Severity: "Moderate",
+				Ends:     &ends,
+				Expires:  &expires,
 				References: []model.AlertReference{
 					{ID: "urn:ref:1", Sent: &sent},
 					{Identifier: "ref-two"},
@@ -145,6 +149,20 @@ func TestMapPostgresEventAlertStructPayload(t *testing.T) {
 	if got := firstAlert.Values["reference_count"]; got != 2 {
 		t.Fatalf("alerts reference_count = %#v, want 2", got)
 	}
+	if got := firstAlert.Values["ends"]; got != ends {
+		t.Fatalf("alerts ends = %#v, want %#v", got, ends)
+	}
+	if got := firstAlert.Values["expires"]; got != expires {
+		t.Fatalf("alerts expires = %#v, want %#v", got, expires)
+	}
+
+	alertWrites := writesForTable(writes, tableAlerts)
+	if len(alertWrites) != 2 {
+		t.Fatalf("alert writes len = %d, want 2", len(alertWrites))
+	}
+	if got := alertWrites[1].Values["ends"]; got != nil {
+		t.Fatalf("second alert ends = %#v, want nil", got)
+	}
 
 	assertAllWritesIncludeAllColumns(t, writes)
 }
@@ -758,6 +776,16 @@ func firstWriteForTable(writes []fksinks.PostgresWrite, table string) (fksinks.P
 	return fksinks.PostgresWrite{}, false
 }
 
+func writesForTable(writes []fksinks.PostgresWrite, table string) []fksinks.PostgresWrite {
+	out := make([]fksinks.PostgresWrite, 0)
+	for _, w := range writes {
+		if w.Table == table {
+			out = append(out, w)
+		}
+	}
+	return out
+}
+
 func assertAllWritesIncludeAllColumns(t *testing.T, writes []fksinks.PostgresWrite) {
 	t.Helper()
 	colCounts := tableColumnCounts()