[Bug] Hide Opus 4.5 upgrade note when already using Opus 4.5

Description

The note "/model to try Opus 4.5. Note: you may need to request access from your cloud provider" is shown even when the user is already using Opus 4.5 via Vertex or other cloud providers (e.g., claude-opus-4-5@20251101).

Expected Behavior

This upgrade note should be hidden when the current model is already Opus 4.5, since it's not relevant to users who are already on the latest model.

Current Behavior

The note appears regardless of which model the user is currently using.

Environment

• Using Opus 4.5 via Vertex (claude-opus-4-5@20251101)