chore: update model manifest

[github-actions]

Automated model discovery run.

This PR updates components/manifests/base/core/models.json based on
probing Vertex AI endpoints. Validation passed — safe to auto-merge.

Unleash flags are synced automatically on deploy by the
sync-model-flags Job.

Diff

diff --git a/components/manifests/base/core/models.json b/components/manifests/base/core/models.json
index 1261068..35f335b 100755
--- a/components/manifests/base/core/models.json
+++ b/components/manifests/base/core/models.json
@@ -229,6 +229,14 @@
       "provider": "google",
       "available": false,
       "featureGated": true
+    },
+    {
+      "id": "claude-fable-5-1",
+      "label": "Claude Fable 5.1",
+      "vertexId": "claude-fable-5-1@default",
+      "provider": "anthropic",
+      "available": false,
+      "featureGated": true
     }
   ]
 }

[ambient-code]

Manifest validation passed — auto-approved by model discovery workflow

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