refactor: report errors through utopia-php/span instead of utopia-php/logger - #9

The error-reporting migration no longer has automated coverage for exporter delivery and filtering.

Replaces logger-based error reporting with request spans and stdout/Sentry exporters, publishing only server errors. Removes GEO_LOGGING_PROVIDER, raises the PHP requirement to 8.4, and updates E2E response-header handling. The final version retains only the E2E suite rather than the previously added unit coverage.