feat(growth): add deterministic forecasting engine

internal/growth/catalog.go

@@ -0,0 +1,37 @@
+package growth
+
+import "time"
+
+const officialCalendarSource = "https://calendar.ut.ac.ir/"
+const curatedCommercialSource = "CURATED_COMMERCIAL_1405_V1"
+
+// Catalog1405 returns a defensive copy of the reviewed initial catalog. Dates are
+// Gregorian Tehran-local calendar dates and cover the imported 1405 history plus
+// the first 90 forecast days after 2026-06-30.
+func Catalog1405() []Event {
+	events := []Event{
+		catalogEvent("nowruz-1405", "نوروز", "2026-03-21", "2026-03-24", "new-year", EventOfficial, []string{"هدیه", "خرید", "سال-نو"}),
+		catalogEvent("nature-day-1405", "روز طبیعت", "2026-04-02", "2026-04-02", "leisure", EventOfficial, []string{"تفریح", "خرید"}),
+		catalogEvent("teachers-day-1405", "روز معلم", "2026-05-02", "2026-05-02", "appreciation", EventOfficial, []string{"هدیه", "آموزش", "قدردانی"}),
+		catalogEvent("khordad-15-1405", "قیام پانزده خرداد", "2026-06-05", "2026-06-05", "official-holiday", EventOfficial, []string{"تعطیل"}),
+		catalogEvent("fathers-day-commercial-1405", "روز پدر", "2026-08-25", "2026-08-25", "appreciation", EventCommercial, []string{"هدیه", "خرید", "قدردانی"}),
+		catalogEvent("back-to-school-1405", "آمادگی بازگشایی مدارس", "2026-09-10", "2026-09-22", "education-season", EventCommercial, []string{"آموزش", "خرید", "مدرسه"}),
+	}
+	return append([]Event(nil), events...)
+}
+
+func catalogEvent(id, title, start, end, family string, kind EventKind, tags []string) Event {
+	source := officialCalendarSource
+	if kind == EventCommercial {
+		source = curatedCommercialSource
+	}
+	return Event{ID: id, TitleFA: title, StartDate: mustCatalogDate(start), EndDate: mustCatalogDate(end), Family: family, Tags: append([]string(nil), tags...), Source: source, Kind: kind}
+}
+
+func mustCatalogDate(value string) time.Time {
+	parsed, err := time.Parse(time.DateOnly, value)
+	if err != nil {
+		panic("invalid reviewed event catalog date: " + value)
+	}
+	return parsed
+}