refactor: centralize event dialog form state

tests/event-dialog.test.tsx

@@ -0,0 +1,16 @@
+import { describe, expect, test } from "bun:test";
+import { getEventFormValuesFromEvent } from "@/lib/event-form";
+
+describe("EventDialog public modes", () => {
+	test("accepts AI-prefilled editable initial values through its public props", () => {
+		const initialValues = getEventFormValuesFromEvent({
+			title: "AI Draft",
+			start: "2026-04-09T10:00:00.000Z",
+			recurrenceRule: "FREQ=WEEKLY;INTERVAL=1;BYDAY=TH",
+		});
+
+		expect(initialValues.title).toBe("AI Draft");
+		expect(initialValues.start).toBe("2026-04-09T10:00:00.000Z");
+		expect(initialValues.recurrenceRule).toBe("FREQ=WEEKLY;INTERVAL=1;BYDAY=TH");
+	});
+});