feat(isac): add avatar oversight queue

docs/DESIGN_SYSTEM.md

@@ -633,3 +633,20 @@ focus-visible outline, provide pressed feedback, and meet a minimum 48-pixel
 tap height. Do not apply this pattern to edit, delete, approve, or other
 mutating actions, and do not stretch a target across rows containing independent
 interactive controls.
+
+### Avatar Oversight
+
+Custom avatars are active immediately and enter a separate Avatar Oversight
+queue. The registry uses compact image-evidence cards rather than a text table:
+portrait, explicit lifecycle state, agent identity, submission time, normalized
+size, reviewer, and note stay visible together. Pending is orange, approved is
+green, and removed is red; withdrawn and superseded remain neutral. State text
+is mandatory.
+
+Review uses the standard ISAC modal and two equal decision controls. Approval
+records the review without changing the active image. Removal requires a reason
+and explicit confirmation, deletes the custom file, and returns the account to
+the default SHD portrait. A stale review must never act on a newer upload.
+Historical entries retain metadata and audit evidence even when their image is
+no longer available. At narrow widths cards become one column, retain a large
+portrait preview, and expose a minimum 44-pixel review action.