Redirect system admin to platform dashboard

app/ui/routes/auth.py

@@ -1,4 +1,4 @@
-from __future__ import annotations
+from __future__ import annotations
 
 from datetime import datetime, timezone, timedelta
 
@@ -125,6 +125,10 @@ def _post_login_redirect(must_change_password: bool, permissions: set[str], role
 
     role_set = set(roles or [])
 
+    # System Admin must land on platform dashboard before employee/self-service routing.
+    if "System Admin" in role_set:
+        return "/system-admin/dashboard"
+
     # Phase 7K refinement:
     # Dedicated Partner users should land directly on Partner Workspace.
     # System/Firm Admin users are not forced here because they keep broader admin context.
@@ -835,3 +839,4 @@ def change_password_required(request: Request):
 def logout(request: Request):
     request.session.clear()
     return RedirectResponse(url="/login", status_code=303)
+