fix(adk): Always inject headers on execute activity

[declan-scale]

Greptile Summary

This PR removes the activity-name allowlist from ContextWorkflowOutboundInterceptor.start_activity, so task_id, trace_id, and parent_span_id headers are now injected into every outbound activity, not just invoke_model_activity / run_claude_agent_activity. This fixes cases where other activities in a workflow needed the same context propagation.

Confidence Score: 5/5

Safe to merge; the only finding is a minor log-level concern that does not affect correctness.

The change is a straightforward removal of an overly-narrow allowlist. The core propagation logic is unchanged and correct. The single finding is a P2 warning-log noise issue that doesn't impact behavior or data integrity.

No files require special attention.

Important Files Changed

Filename	Overview
src/agentex/lib/core/temporal/plugins/openai_agents/interceptors/context_interceptor.py	Removes the activity-name allowlist filter so that task_id/trace_id/parent_span_id headers are injected on every outbound activity start, not just named model activities. The logic itself is correct, but the warning log that fires when context attributes are absent will now trigger for all non-model workflows, potentially causing log noise.

Prompt To Fix All With AI

Fix the following 1 code review issue. Work through them one at a time, proposing concise fixes.

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### Issue 1 of 1
src/agentex/lib/core/temporal/plugins/openai_agents/interceptors/context_interceptor.py:103
**Warning log noise for non-context workflows**

Now that headers are injected for _all_ activities (not just model activities), workflows that legitimately have no `_task_id`/`_trace_id`/`_parent_span_id` will emit a `WARNING` for every single activity they start. This can flood logs with spurious warnings that aren't actionable. Consider downgrading this branch to `DEBUG` since "no context found" is now expected for non-model workflows.

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