fix(output): throw server error for streamed exceptions

[simPod]

Context

ClickHouse can emit streamed exception frames after response headers. JsonEachRow currently attempts to decode those frames as JSON, surfacing a JsonException instead of the client-level ServerError.

Decision

Detect exception frames while consuming JSONEachRow lines and rethrow them through ServerError::fromResponseContent().

Consequences

• Streaming JSONEachRow consumers preserve ClickHouse server-error semantics.
• Both string and stream-backed JSONEachRow outputs handle streamed exception frames consistently.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 95.99%. Comparing base (725353b) to head (8ee28f5).

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #336      +/-   ##
==========================================
+ Coverage   95.94%   95.99%   +0.04%     
==========================================
  Files          42       42              
  Lines         839      848       +9     
==========================================
+ Hits          805      814       +9     
  Misses         34       34              

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