Preserve baggage for automatic Sentry events

[vrslev]

Summary

• snapshot configured OpenTelemetry baggage on escaping exceptions before baggage scopes detach
• enrich later automatic Sentry events from the exception snapshot and remove stale configured fields
• traverse causes, contexts, nested ExceptionGroup children, and cycles
• preserve innermost nested-scope values without leaking caught or concurrent exceptions
• require no service-level capture_exception or asyncio integration workaround

Verification

• just lint-ci
• just test: 216 passed, 99% coverage
• real Sentry Excepthook + asyncio.TaskGroup probe: one automatic ExceptionGroup event retained conversation_id without capture_exception
• sentry-sdk 2.7.0 compatibility probe
• concurrent FastStream, nested-scope, delayed-capture, chain, cycle, and ExceptionGroup regressions
• fresh independent review: no material findings

Jira VA-7612

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.

Flag	Coverage Δ
unittests	99.00% <100.00%> (+0.04%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Files with missing lines	Coverage Δ
...obootstrap/instruments/opentelemetry_instrument.py	98.63% <100.00%> (+0.04%)	⬆️
microbootstrap/instruments/sentry_instrument.py	98.57% <100.00%> (+0.87%)	⬆️

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[vrslev]

Agent:

Closing this draft. The service-level conversation scopes will bind configured baggage to the existing request/message Sentry isolation scope, so automatic framework and logging capture does not need exception snapshots or explicit capture_exception.

[vrslev]

Agent:

Reopening after verifying the real Back TaskGroup lifecycle. Automatic top-level Sentry capture receives an ExceptionGroup, so the generic snapshot lookup must traverse nested exceptions. The added regression and real Excepthook probe pass without service-level capture_exception or enable_asyncio_integration.