docs: add internal service reconciliation to OBS.11a recovery examples

[detail-app]

The OBS.11a invariant only mentioned "claimed outbox residue" as an example
of an explicit recovery diagnostic that can synthesize terminal failure.
This was incomplete after commit ed8554e added new behavior where stale
internal service rows can be reconciled as failed via
superseded_internal_service_record or internal_service_runtime_missing_after_stale_window.

An agent reading only OBS.11a might incorrectly conclude that stale internal
service reconciliation is prohibited from synthesizing terminal failure,
since it wouldn't recognize these new diagnostics as valid exceptions.

Introduced by commit ed8554e (@VanL)

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 80.40%. Comparing base (06d8db5) to head (551f473).

Additional details and impacted files

@@            Coverage Diff             @@
##             main      #24      +/-   ##
==========================================
+ Coverage   80.37%   80.40%   +0.03%     
==========================================
  Files         160      160              
  Lines       29641    29641              
==========================================
+ Hits        23824    23833       +9     
+ Misses       5817     5808       -9     

Flag	Coverage Δ
unittests	80.40% <ø> (+0.03%)	⬆️

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see 5 files with indirect coverage changes

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