Restore E2B provisioner static analysis after response narrowing #22

The Sonar integration exposed the same existing PHPStan failure on all three maintained PHP/Laravel jobs: E2bSandboxProvider.php:109 checks is_array($body) again after nonempty sandboxID validation has already established that fact. The invalid-response guard at the first read remains necessary.

Remove only the redundant second conditional, retain malformed/missing-ID refusal and default-template metadata, and verify with fake HTTP responses plus the normal formatting/static/test matrix. No real E2B calls, provider provisioning, credentials or dependency constraints need to change. This restores the existing CI gate and unblocks the Sonar rollout in #21; it is not evidence of a customer provisioning failure.