feat: simplify mails and add reminders

packages/db/src/migrations/0009_reminder_24h.sql

@@ -0,0 +1,2 @@
+-- Add sent_24h_at column to track whether the 24-hour-before reminder was sent
+ALTER TABLE `reminder` ADD `sent_24h_at` integer;

packages/db/src/schema/reminders.ts

@@ -6,6 +6,9 @@ export const reminder = sqliteTable(
 	{
 		id: text("id").primaryKey(), // UUID
 		email: text("email").notNull(),
+		/** Set when the 24-hours-before reminder has been sent. */
+		sent24hAt: integer("sent_24h_at", { mode: "timestamp_ms" }),
+		/** Set when the 1-hour-before reminder has been sent. */
 		sentAt: integer("sent_at", { mode: "timestamp_ms" }),
 		createdAt: integer("created_at", { mode: "timestamp_ms" })
 			.default(sql`(cast(unixepoch('subsecond') * 1000 as integer))`)