Add poller_autoscaling_auto_enroll namespace capability (#803)

## What
Add a new `poller_autoscaling_auto_enroll` boolean field to
`NamespaceInfo.Capabilities`.

## Why
Today, poller autoscaling requires explicit SDK-side opt-in via worker
options. This capability lets the server tell SDKs to automatically
enroll workers in poller autoscaling for specific namespaces, controlled
by a namespace-scoped dynamic config — no user code changes needed.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

---------

Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>

Author: rkannan82

openapi/openapiv2.json

@@ -16739,6 +16739,10 @@
         "workflowUpdateCallbacks": {
           "type": "boolean",
           "title": "True if the namespace supports attaching callbacks on workflow updates"
+        },
+        "pollerAutoscalingAutoEnroll": {
+          "type": "boolean",
+          "description": "When true, workers should use poller autoscaling by default unless explicitly configured otherwise."
         }
       },
       "description": "Namespace capability details. Should contain what features are enabled in a namespace."

openapi/openapiv3.yaml

@@ -13141,6 +13141,9 @@ components:
         workflowUpdateCallbacks:
           type: boolean
           description: True if the namespace supports attaching callbacks on workflow updates
+        pollerAutoscalingAutoEnroll:
+          type: boolean
+          description: When true, workers should use poller autoscaling by default unless explicitly configured otherwise.
       description: Namespace capability details. Should contain what features are enabled in a namespace.
     NamespaceInfo_Limits:
       type: object

temporal/api/namespace/v1/message.proto

@@ -56,6 +56,8 @@ message NamespaceInfo {
         bool standalone_nexus_operation = 11;
         // True if the namespace supports attaching callbacks on workflow updates
         bool workflow_update_callbacks = 12;
+        // When true, workers should use poller autoscaling by default unless explicitly configured otherwise.
+        bool poller_autoscaling_auto_enroll = 13;
     }
 
     // Namespace configured limits