Feedback submission now checks the organization policy at the point of sending

Sending feedback goes through an allow_product_feedback organization policy check in the low-level send helper, which previously did no policy check of its own. When the policy is off it fails with a policy_blocked reason and you see a message saying feedback is disabled by your organization's policy. The policy key itself is long-standing, so this closes a gap at one call path rather than adding a new restriction.