Configurable table-change notification schedule

Company admins can now configure the weekdays, start time, and timezone for table-change notifications from Company settings. Other team members can view the effective schedule, and Artie validates changes and avoids duplicate checks when the schedule is edited.

Why this matters

• Receive schema-change notifications when your team is ready to act
• Avoid alerts during weekends or outside business hours
• Give admins a clear, human-readable view of the active schedule