feat(logs): add NLog integration

[Flash0ver]

closes #5167

Changes

Add NLog integration to Sentry Structured Logging.

Docs

• docs(dotnet/logs): add NLog structured logs integration sentry-docs#18738

See also

• fix: populate Default attributes on structured logs from current scope #5216

Implementation notes

SentryTarget is an NLog target. Every log NLog routes to it lands in InnerWrite (SentryTarget.cs:331), which now fans out to two independent pipelines:

1. Classic path (pre-existing): logEvent → Sentry event (if Level >= MinimumEventLevel) and/or breadcrumb.
2. Structured-logs path (this PR): logEvent → Sentry structured log, gated on EnableLogs.

The two are additive and independently gated — enabling logs doesn't change event/breadcrumb behavior.

The dispatch gate

While the classic path continues to be gated by MinimumEventLevel, a new EnableLogs property has been added to determine whether structured logs are created from NLog logs:

var sentryOptions = hub.GetSentryOptions();
if (sentryOptions?.EnableLogs is true)
    CaptureStructuredLog(hub, sentryOptions, logEvent);

NLog-specifics

CaptureStructuredLog (SentryTarget.Structured.cs) translates NLog's LogEventInfo into a SentryLog.

The NLog-specific concerns:

NLog concept	Sentry structured-log field	Handling
logEvent.Level (NLog.LogLevel)	level	ToSentryLogLevel() maps Trace/Debug/Info/Warn/Error/Fatal; Off → null → drop (LogLevelExtensions.cs:33).
logEvent.FormattedMessage (rendered)	body (message)	The message with arguments already substituted.
logEvent.Message (raw template)	template	e.g. "User {UserId} logged in".
logEvent.MessageTemplateParameters	parameters (→ sentry.message.parameter.*)	e.g. UserId . Note that NLog also allows unnamed parammeters to be passed like {}. These have an empty name so GetParameters falls back to the positional index as the name, to avoid collisions.
logEvent.Properties	property.* attributes	NLog's structured/context properties. GetStructuredLoggingParametersAndAttributes filters out null/blank keys and any key already used as a message parameter (!parameterNames.Contains(key)) so a value isn't emitted twice.
logEvent.LoggerName	category.name attribute	The source logger identifier.
logEvent.TimeStamp (DateTime)	timestamp	Wrapped into a DateTimeOffset.

Everything else — Environment, Release, SDK name/version, server.address, user.* — comes from SetDefaultAttributes(options, scope, Sdk), shared with all integrations, plus SetOrigin("auto.log.nlog").

[codecov]

Codecov Report

❌ Patch coverage is 92.00000% with 6 lines in your changes missing coverage. Please review.
✅ Project coverage is 77.31%. Comparing base (b006e95) to head (842e133).
⚠️ Report is 3 commits behind head on main.

Files with missing lines	Patch %	Lines
src/Sentry.NLog/LogLevelExtensions.cs	72.72%	2 Missing and 1 partial ⚠️
src/Sentry.NLog/SentryTarget.Structured.cs	94.87%	1 Missing and 1 partial ⚠️
src/Sentry.NLog/SentryTarget.cs	94.11%	0 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #5176      +/-   ##
==========================================
+ Coverage   74.23%   77.31%   +3.08%     
==========================================
  Files         509      421      -88     
  Lines       18435    15691    -2744     
  Branches     3610     3125     -485     
==========================================
- Hits        13685    12132    -1553     
+ Misses       3875     2826    -1049     
+ Partials      875      733     -142     

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[jamescrosswell]

Overall looks pretty good. No blocking comments from me - mostly stylistic.

The main one that needs to be dealt with is the one that the Sentry bot called out since that would be a bug for certain initialisation paths.