feat: Keep override-affected evaluations out of individual events

[kinyoklion]

Summary

This PR is based on the override store branch because it consumes the override marking that branch produces on evaluation results.

This change adds the analytics event behavior of the OVERRIDE specification to the shared event code and the Node.js server SDK.

An evaluation marked as override-affected produces no individual feature event and no debug event, even when the flag requests them. It is still counted in summary events like any other evaluation, in a separate counter that carries the overrideAffected marker. The marker is part of the summary aggregation key, so override-affected and other evaluations of the same flag, variation, and version accumulate into separate counters rather than collapsing together. The marker is present on a counter only when true, like the existing unknown marker.

The client hands the marking to the event processor as a scalar on the input event, taken from the evaluation result. Event generation does not read the evaluation reason. The record of a prerequisite evaluation carries the prerequisite's own marking, so an unaffected prerequisite inside a marked top-level evaluation still produces its individual event, while a marked prerequisite record produces none and is counted under the marked counter for the prerequisite flag.

The shared event summarizer and processor are also used by the client-side SDKs. The new field is optional and those SDKs never set it, so their output is unchanged.

The OVERRIDE test vector runner now also asserts the marking of the summary counter that each evaluation contributes to, by flushing the events and reading the summary payload.

SDK-3247

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Note

Overview
Implements OVERRIDE-spec analytics for evaluations touched by the override store: the server SDK passes an overrideAffected flag from the evaluation result into event creation (not from the reason), including per-prerequisite records with each prereq’s own marking.

Override-affected evaluations are still included in summary events but are excluded from individual feature and debug events even when trackEvents / debug mode would normally emit them. The summarizer treats overrideAffected as part of the aggregation key, so marked and unmarked evaluations of the same flag/variation/version land in separate counters; the summary payload sets overrideAffected: true only on marked counters.

Shared EventFactoryBase / InputEvalEvent plumbing carries the optional field (client SDKs never set it, so behavior there is unchanged). Tests cover the shared processor/summarizer, end-to-end server override scenarios (including prereq trees), and OVERRIDE vectors asserting summaryOverrideAffected after flush.

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Uncompressed size: 132642 bytes

[github-actions]

@launchdarkly/js-client-sdk size report
This is the brotli compressed size of the ESM build.
Compressed size: 32691 bytes
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Uncompressed size: 117095 bytes

[github-actions]

@launchdarkly/js-client-sdk-common size report
This is the brotli compressed size of the ESM build.
Compressed size: 25437 bytes
Compressed size limit: 44000
Uncompressed size: 165420 bytes

[kinyoklion]

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