Notification when affiliate commission structure is overridden

When a program owner overrides an affiliate’s commission structure (e.g. custom rate), the affiliate is not notified. The new rate applies silently.

Proposed Solution:
Add an optional setting to notify affiliates when:

• Their commission rate is changed

• They are moved to a different group with a different commission structure

• A custom override is applied

Optional enhancements:

• Email notification toggle (on/off)

• Optional note/reason from program owner

• Change history visible to affiliate and program owner