overview: exclude sandbox teams from the agents list, and name agents for display

sandbox:librechat-test is a throwaway test account rather than an agent of the co-op,
so it drops out of the panel. Its spend then appears nowhere — accepted knowingly.

Agents also carry a display `name` (the alias minus its "agent:" prefix), so the panel
does not have to strip prefixes itself.

app/main.py

@@ -3137,12 +3137,18 @@ async def admin_overview(request: Request):
     agents = [
         {
             "alias": alias,
+            # Display name: the panel's section header already says "Agents", so the
+            # "agent:" prefix is noise there. `alias` keeps the full string.
+            "name": alias.split(":", 1)[1] if ":" in alias else alias,
             "spend": float(t.get("spend") or 0.0),
             "budget": t.get("max_budget"),
             "team_members": len(t.get("members_with_roles") or []),
         }
         for alias, t in teams.items()
-        if alias and not alias.startswith("member:")
+        # member:* are members; sandbox:* are throwaway test accounts rather than
+        # agents of the co-op. Their spend stops being visible anywhere once
+        # filtered here — accepted knowingly.
+        if alias and not alias.startswith(("member:", "sandbox:"))
     ]
     agents.sort(key=lambda a: a["spend"], reverse=True)