fix: Include screenshot attachment in native backend envelope

[tustanivsky]

Summary

The native backend's crash daemon captures screenshot out-of-process via sentry__screenshot_capture() and saves it to {run_folder}/screenshot.png. However, neither write_envelope_with_native_stacktrace nor write_envelope_with_minidump included this file in the envelope. After the envelope was sent, the run folder was cleaned up deleting the screenshot that was never transmitted.

The crashpad and breakpad backends handle this correctly: crashpad passes the screenshot path to StartHandler() and breakpad explicitly calls sentry__envelope_add_attachment().

Suggested fix

Both envelope writing functions now check for screenshot.png in the run folder and add it via the existing
write_attachment_to_envelope() helper which gracefully skips missing files. This follows the same pattern used for scope attachments read from the __sentry-attachments metadata file.

Related items

• Add out-of-process screenshot capturing on Windows sentry-unreal#1325

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[jpnurmi]

does this fix the screenshot test for native? are we able to remove the skip?

sentry-native/tests/test_integration_screenshot.py

Lines 43 to 48 in e12743b

	pytest.param(
	{"SENTRY_BACKEND": "native"},
	marks=pytest.mark.skip(
	reason="Native backend screenshot needs testing on Windows machine"
	),
	),

[tustanivsky]

does this fix the screenshot test for native? are we able to remove the skip?

The file-existence test still has to be skipped for native backend since the daemon deletes the run folder after processing the envelope. So basically by the time we check for the file it's already gone.