feat(schedules): add timezone support for scheduled jobs and update database schema

- Introduced a new `commonTimezones` array for timezone selection in the UI.
- Updated the schedule form to include an optional timezone field.
- Modified the database schema to add a `timezone` column to the `schedule` table.
- Enhanced the scheduling logic to utilize the specified timezone, defaulting to UTC if not provided.

packages/server/src/db/schema/schedule.ts

@@ -49,6 +49,7 @@ export const schedules = pgTable("schedule", {
 		onDelete: "cascade",
 	}),
 	enabled: boolean("enabled").notNull().default(true),
+	timezone: text("timezone"),
 	createdAt: text("createdAt")
 		.notNull()
 		.$defaultFn(() => new Date().toISOString()),