Clear App Limit

PREVIEW. This endpoint is deployed but gated: it returns 404 unless the hosted app platform is enabled for your organization. It is published here so the contract describes the whole surface, not so it can be called today.

Remove every window's cap for this app, returning it to uncapped.

A DELETE rather than PUT {"credit_cap": 0}, because absence of a row IS "no cap" (contracts.py:655) and zero is a real cap meaning "allow nothing". Collapsing the two would make an accidental zero indistinguishable from uncapped, in the one place where guessing wrong costs money.

Idempotent: clearing an app that has no cap succeeds.