Implemented the weather forecast discussion product from weatherfeeder v0.8.3

internal/adapters/inbound/httpapi/presenter/payload_test.go

@@ -175,6 +175,40 @@ func TestForecastPayloadNoTimezonePreservesUTCAndCopySemantics(t *testing.T) {
 	assertOffsetSeconds(t, metric.Periods[0].StartTime, 0)
 }
 
+func TestDiscussionPayloadTimezoneConversionAndCopySemantics(t *testing.T) {
+	loc := time.FixedZone("UTC-05:00", -5*60*60)
+	issuedAt := time.Date(2026, 7, 10, 12, 0, 0, 0, time.UTC)
+	updatedAt := issuedAt.Add(30 * time.Minute)
+	shortIssuedAt := issuedAt.Add(-15 * time.Minute)
+	run := &model.WeatherForecastDiscussion{
+		OfficeID:    "LSX",
+		Product:     model.ForecastDiscussionProductAFD,
+		IssuedAt:    issuedAt,
+		UpdatedAt:   &updatedAt,
+		KeyMessages: []string{"msg one"},
+		ShortTerm:   &model.WeatherForecastDiscussionSection{Qualifier: "(Tonight)", IssuedAt: &shortIssuedAt, Text: "Short term text"},
+	}
+
+	payload := DiscussionPayload(run, UnitsMetric, loc)
+	discussion, ok := payload.(*model.WeatherForecastDiscussion)
+	if !ok {
+		t.Fatalf("expected *model.WeatherForecastDiscussion payload, got %T", payload)
+	}
+	if discussion == run {
+		t.Fatalf("expected discussion payload to be copied")
+	}
+	if discussion.ShortTerm == run.ShortTerm {
+		t.Fatalf("expected shortTerm pointer to be copied")
+	}
+	assertOffsetSeconds(t, discussion.IssuedAt, -5*60*60)
+	assertOffsetSeconds(t, *discussion.UpdatedAt, -5*60*60)
+	assertOffsetSeconds(t, *discussion.ShortTerm.IssuedAt, -5*60*60)
+	if discussion.KeyMessages[0] != "msg one" {
+		t.Fatalf("expected key message preserved, got %#v", discussion.KeyMessages)
+	}
+	assertOffsetSeconds(t, run.IssuedAt, 0)
+}
+
 func TestMetricCopyAndNilHandling(t *testing.T) {
 	obs := &model.WeatherObservation{
 		TemperatureC: float64Ptr(20.6),
@@ -202,6 +236,9 @@ func TestMetricCopyAndNilHandling(t *testing.T) {
 	if AlertsPayload(nil, UnitsUS) != nil {
 		t.Fatalf("expected nil alerts input to return nil payload")
 	}
+	if DiscussionPayload(nil, UnitsUS, nil) != nil {
+		t.Fatalf("expected nil discussion input to return nil payload")
+	}
 	if CurrentConditionsPayload(nil, UnitsUS, 0) != nil {
 		t.Fatalf("expected nil current conditions input to return nil payload")
 	}