feat(worker): scaffold activities, workflows, worker entrypoint — T13

src/activity_core/activities.py:
  - load_activity_definition, resolve_context, log_run — @activity.defn
    stubs (raise NotImplementedError, bodies in T14–T17)

src/activity_core/workflows.py:
  - RunActivityWorkflow (orchestrator-tq) — @workflow.defn stub (T18)
  - TaskExecutorWorkflow (task-execution-tq) — @workflow.defn stub (T19)

src/activity_core/worker.py:
  - Connects to Temporal via TEMPORAL_HOST / TEMPORAL_NAMESPACE env vars
  - Spawns two Workers: orchestrator-tq and task-execution-tq
  - Runs until cancelled (python -m activity_core.worker)

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/activity_core/worker.py

@@ -0,0 +1,66 @@
+"""Temporal worker entrypoint for activity-core.
+
+Starts two workers (wired up in T20):
+  - orchestrator-tq: RunActivityWorkflow + its activities
+  - task-execution-tq: TaskExecutorWorkflow
+
+Run with:
+    TEMPORAL_HOST=localhost:7233 \
+    ACTCORE_DB_URL=postgresql+asyncpg://actcore:actcore@localhost:5433/actcore \
+        python -m activity_core.worker
+
+Environment variables:
+    TEMPORAL_HOST      Temporal frontend address (default: localhost:7233)
+    TEMPORAL_NAMESPACE Temporal namespace       (default: default)
+    ACTCORE_DB_URL     App DB connection string (required)
+"""
+
+from __future__ import annotations
+
+import asyncio
+import os
+
+from temporalio.client import Client
+from temporalio.worker import Worker
+
+from activity_core.activities import (
+    load_activity_definition,
+    log_run,
+    resolve_context,
+)
+from activity_core.workflows import RunActivityWorkflow, TaskExecutorWorkflow
+
+TEMPORAL_HOST = os.environ.get("TEMPORAL_HOST", "localhost:7233")
+TEMPORAL_NAMESPACE = os.environ.get("TEMPORAL_NAMESPACE", "default")
+
+ORCHESTRATOR_TASK_QUEUE = "orchestrator-tq"
+TASK_EXECUTION_TASK_QUEUE = "task-execution-tq"
+
+
+async def run() -> None:
+    client = await Client.connect(TEMPORAL_HOST, namespace=TEMPORAL_NAMESPACE)
+
+    orchestrator_worker = Worker(
+        client,
+        task_queue=ORCHESTRATOR_TASK_QUEUE,
+        workflows=[RunActivityWorkflow],
+        activities=[load_activity_definition, resolve_context, log_run],
+    )
+
+    task_worker = Worker(
+        client,
+        task_queue=TASK_EXECUTION_TASK_QUEUE,
+        workflows=[TaskExecutorWorkflow],
+        activities=[],
+    )
+
+    async with orchestrator_worker, task_worker:
+        print(
+            f"Workers running — queues: {ORCHESTRATOR_TASK_QUEUE!r}, "
+            f"{TASK_EXECUTION_TASK_QUEUE!r} (namespace={TEMPORAL_NAMESPACE!r})"
+        )
+        await asyncio.Future()  # run until cancelled
+
+
+if __name__ == "__main__":
+    asyncio.run(run())