Fix late webview completion race

[e271828-]

Summary

This fixes the late-completion race behind the flaky HCaptchaWebViewManager__Tests.test__Configure_Web_View failure seen in GitHub Actions job 67922018521, while keeping HCaptcha__Bench.testBenchVerify measuring webview startup plus verification.

Reference:

• https://github.com/hCaptcha/HCaptcha-ios-sdk/actions/runs/23348009687/job/67922018521

Root Cause

HCaptchaWebViewManager kept the active validation completion alive after delivering a terminal result.

That allowed later WKNavigationDelegate callbacks, especially webViewWebContentProcessDidTerminate, to re-enter the same completion path with an error result after success had already been delivered.

The earlier branch version tried to hide that race by preloading the benchmark before measureMetrics, but that changed what testBenchVerify measures. We do not want that benchmark warmed up ahead of time.

What Changed

• Terminal result delivery now goes through complete(...), which clears the stored completion before invoking it.
• validate(on: nil) now uses the same terminal completion path for .failedSetup.
• stop() clears any pending completion so post-stop callbacks cannot leak through.
• The benchmark warmup added in this branch was removed, so testBenchVerify still includes webview startup time.
• The regression test test__Validate__Ignores_Late_Termination_After_Token remains to cover the late-termination case directly.

Validation

Ran locally:

• xcodebuild test -workspace Example/HCaptcha.xcworkspace -scheme HCaptcha_Tests -destination 'platform=iOS Simulator,id=AD95999C-D8DE-4206-848B-AF7EC34B7EA9' -only-testing 'HCaptcha_Tests/HCaptchaWebViewManager__Tests/test__Validate__Ignores_Late_Termination_After_Token' -only-testing 'HCaptcha_Tests/HCaptchaWebViewManager__Tests/test__Configure_Web_View' -only-testing 'HCaptcha_Tests/HCaptchaWebViewManager__Tests/test__Stop'
• xcodebuild test -workspace Example/HCaptcha.xcworkspace -scheme HCaptcha_Tests -destination 'platform=iOS Simulator,id=AD95999C-D8DE-4206-848B-AF7EC34B7EA9' -only-testing 'HCaptcha_Tests/HCaptcha__Bench/testBenchVerify'

Both passed.

[github-actions]

Cocoapods size report:

OLD: 146409 bytes
NEW: 163393 bytes

DIFF: 16984 bytes

[e271828-]

draft, as we may want to keep recording including the initial load cost.