[breaking] Google shuts down gemini-robotics-er-1.5-preview

gemini-robotics-er-1.5-preview was announced April 14, 2026 for shutdown April 30, 2026 at 9AM PST. No replacement is named. Effective: 2026-04-30. Affected: google/gemini-robotics-er-1.5-preview. Severity: breaking. Verification: verified.