docs: drop the banner screenshot assets

The six PNGs were committed only to embed in the PR description. The Storybook
stories they were captured from are the reproducible artifact and stay.

Author: dante01yoon

.github/pr-assets/banner-ending-owner.png

@@ -25,9 +25,10 @@ export interface BillingBannerInputs {
 }
 
 // The single billing banner slot, in priority order: paused > paymentFailed >
-// outOfCredits > ending. Gated on the team PLAN, not the workspace type: a team
-// workspace can sit on a personal-tier legacy plan, and a personal workspace can
-// hold a team plan.
+// outOfCredits > ending. Gated on the team PLAN, because plan and workspace type
+// are independent axes: a team workspace can sit on a personal-tier legacy plan
+// today, and personal workspaces are due to gain team plans (BE-1526), at which
+// point a workspace-type gate would hide the banner from real team subscribers.
 export function deriveBillingBanner(
   inputs: BillingBannerInputs
 ): BillingBannerKind | null {