fix: exceptions thrown from BeforeBreadcrumb, log filters and BeforeScreenshotCapture no longer reach the application

[jamescrosswell]

Finishes work item 1 ("isolate the callbacks that can reach the host app") of #5535. #5545 already covered TracesSampler on all three paths; this covers the remaining five boxes.

Each callback now runs inside a recovery boundary that logs an error naming the callback and applies the fallback the Callback Error Isolation spec asks for. Nothing changes for anyone whose callbacks don't throw, and there's no public API change.

Callback	Site	Fallback on failure
BeforeBreadcrumb	Scope.AddBreadcrumb	drop the breadcrumb
BeforeBreadcrumb	Platforms/Android/Callbacks/BeforeBreadcrumbCallback	return null — drop the breadcrumb
BeforeBreadcrumb	Platforms/Cocoa/SentrySdk	return null — drop the breadcrumb
ILogEntryFilter.Filter	Sentry.Extensions.Logging/SentryLogger	drop the log entry
SetBeforeScreenshotCapture	Sentry.Maui/Internal/SentryMauiScreenshotProcessor	skip the screenshot, keep the event

Notes for review:

• Scope.AddBreadcrumb was only accidentally isolated before: HubExtensions.AddBreadcrumb happens to route through Hub.ConfigureScope's catch-all, but Scope.AddBreadcrumb is public and a direct call was unprotected — and the catch-all's "Failure to ConfigureScope" doesn't tell anyone their breadcrumb callback is broken.
• A throwing ILogEntryFilter drops the entry, rather than letting it through as "did not filter". That was review feedback, and the argument for it is that before this PR the exception reached the app and nothing was sent — so failing open would have changed the data behaviour on top of fixing the crash, in the direction that leaks. A filter written to exclude entries would, once broken, start sending them. Dropping keeps the old outcome and only removes the crash. It also matches the spec rationale for filters and what fix: an exception in BeforeSend or BeforeSendTransaction now drops the item instead of sending it #5610 does for BeforeSend. (Conform to the callback error isolation spec (wrap all user callbacks) #5535 proposed "treat as did not filter"; ILogEntryFilter isn't in the spec matrix, so that line was a judgement call rather than anything normative, and it was the wrong one.)
• Filters are now evaluated once per log entry instead of twice. ShouldCaptureEvent and ShouldAddBreadcrumb each ran the whole chain, so user filter code was invoked twice for any entry clearing both thresholds — and, once failures are logged, logged twice. Their shared tail is now a single early return in Log, leaving the two predicates to test only their own level threshold. Never zero: IsEnabled already guarantees at least one threshold is met, so anything reaching that line evaluated the chain at least once before.
• The internal screenshot-callback names now match the public SetBeforeScreenshotCapture (BeforeCaptureInternal → BeforeScreenshotCaptureInternal), and a doc sample calling a non-existent SetBeforeCapture is fixed. The public parameter is still named beforeCapture — parameter names are in the API approval snapshots and renaming breaks named arguments, so that's left alone.
• SetBeforeScreenshotCapture previously unwound to the Hub.CaptureEvent catch-all and dropped the whole event, losing the error the user was trying to report.
• No client-report changes here: BeforeBreadcrumb has no report in the spec matrix, and ILogEntryFilter/SetBeforeScreenshotCapture aren't in it. Work items 2 (fix: telemetry dropped by user callbacks and by validation is now counted in client reports #5607) and 3 (fix: an exception in BeforeSend or BeforeSendTransaction now drops the item instead of sending it #5610) of Conform to the callback error isolation spec (wrap all user callbacks) #5535 cover the reports and the BeforeSend alignment, so this doesn't close the issue.
• The Android bridge is covered by device tests (BeforeBreadcrumbCallbackTests, run on API 34 and 36 across net9.0/net10.0). The Cocoa bridge isn't: its BeforeBreadcrumb is a lambda assigned inline in InitSentryCocoaSdk with no seam to invoke without initialising the native SDK. Extracting it would make it testable the same way — worth doing, but as its own change.

🤖 Generated with Claude Code

[codecov]

Codecov Report

❌ Patch coverage is 90.00000% with 3 lines in your changes missing coverage. Please review.
✅ Project coverage is 74.91%. Comparing base (7a6db80) to head (5e6a369).
⚠️ Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
...try.Maui/Internal/SentryMauiScreenshotProcessor.cs	75.00%	1 Missing and 1 partial ⚠️
src/Sentry.Extensions.Logging/SentryLogger.cs	92.85%	0 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #5606      +/-   ##
==========================================
+ Coverage   74.84%   74.91%   +0.07%     
==========================================
  Files         515      515              
  Lines       18962    18966       +4     
  Branches     3694     3696       +2     
==========================================
+ Hits        14192    14209      +17     
+ Misses       3892     3877      -15     
- Partials      878      880       +2     

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[ric-oliv]

Looks good! Just one comment about the naming.