Add history propagation

[acroca]

Description

Adds workflow history propagation to dapr-ext-workflow.

A workflow can opt into propagating its execution history to a child workflow or activity via propagation=PropagationScope.OWN_HISTORY or propagation=PropagationScope.LINEAGE on call_activity / call_child_workflow.

The receiver reads the propagated chunk through ctx.get_propagated_history() and queries it with PropagatedHistory.get_workflow_by_name(...) → WorkflowResult.get_activity_by_name(...) / .get_child_workflow_by_name(...).

Public surface lives in dapr.ext.workflow.propagation and is re-exported from dapr.ext.workflow — users never need to import from _durabletask. Default behavior is unchanged: propagation=None propagates nothing.

Requires a Dapr sidecar built with history propagation support (durabletask-go #85+ / runtime 1.18+). Against an older sidecar the propagation field is silently dropped and get_propagated_history() returns None.

Includes an example app at examples/workflow/history_propagation.py.

References

• Go SDK reference: wf history ctx propagation durabletask-go#85
• Proto changes: wf history context propagation protos durabletask-protobuf#38

[codecov]

Codecov Report

❌ Patch coverage is 71.40696% with 189 lines in your changes missing coverage. Please review.
✅ Project coverage is 81.89%. Comparing base (bffb749) to head (f492eed).
⚠️ Report is 126 commits behind head on main.

Files with missing lines	Patch %	Lines
.../_durabletask/internal/orchestrator_service_pb2.py	1.61%	61 Missing ⚠️
...rkflow/_durabletask/internal/history_events_pb2.py	3.44%	56 Missing ⚠️
...orkflow/_durabletask/internal/orchestration_pb2.py	4.00%	24 Missing ⚠️
.../_durabletask/internal/orchestrator_actions_pb2.py	4.54%	21 Missing ⚠️
.../workflow/_durabletask/internal/attestation_pb2.py	42.85%	16 Missing ⚠️
...dapr-ext-workflow/dapr/ext/workflow/propagation.py	96.52%	5 Missing ⚠️
...-workflow/dapr/ext/workflow/_durabletask/worker.py	75.00%	3 Missing ⚠️
...xt-workflow/dapr/ext/workflow/_durabletask/task.py	88.88%	1 Missing ⚠️
...ext-workflow/dapr/ext/workflow/workflow_context.py	75.00%	1 Missing ⚠️
...kflow/tests/durabletask/test_propagation_wiring.py	98.94%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1025      +/-   ##
==========================================
- Coverage   86.63%   81.89%   -4.74%     
==========================================
  Files          84      142      +58     
  Lines        4473    13977    +9504     
==========================================
+ Hits         3875    11446    +7571     
- Misses        598     2531    +1933     

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