Reconcile Entitlement

Re-read this user's plan from the provider and return the refreshed entitlement.

A second, independent path to the same truth as the webhook — and the one the post-checkout redirect uses. The two race by design: Polar sends the browser back the moment payment clears, which can beat customer.state_changed reaching us. Worse, the webhook may never arrive at all (no dead-letter queue, no replay, and an endpoint auto-disabled after 10 failures), which leaves a paying user on the free tier with nothing to retry.

Pulling on the success screen closes both holes: the common case is a few hundred milliseconds faster, and the pathological case self-heals instead of becoming a support ticket.

Idempotent — it applies the same full snapshot the webhook would.