Enrich worker failure reporting

[reneklacan]

Summary

• add a RuntimeBuilder failure-reporting hook that preserves concrete worker errors and exposes structured job, batch, retry, terminal, and argument metadata
• enrich default Sentry events on an isolated per-execution hub while preserving worker breadcrumbs and scope context
• defer panic-integration events until reporter selection, preserving the original panic stacktrace while still reporting exactly once
• build failure metadata only on failed executions and keep custom reporters in full control of argument redaction
• add focused coverage for returned errors, batches, retries, custom reporters, scope isolation, panic stacktraces, panic replacement, and builds without Sentry

Testing

• cargo fmt --all -- --check
• cargo clippy --all-features --workspace --all-targets -- -D warnings
• cargo test
• cargo check --all
• cargo check -p oxana --no-default-features

[cursor]

Cursor Bugbot has reviewed your changes using default effort and found 1 potential issue.

^{❌ Bugbot Autofix is OFF. To automatically fix reported issues with cloud agents, enable autofix in the Cursor dashboard.}

^{Reviewed by Cursor Bugbot for commit 29e001e. Configure here.}