feat(plugins): renew the background budget while a task reports (#2055)

Closes #2053

A call that begins a background task gets the longer `background` budget, but it was armed once, so a task that kept calling `report` was still killed at the first deadline. Each `report` and `is-cancelled` now renews it (the deadline only moves forward; silent work still times out), up to a 30-minute ceiling per task. User Cancel, disable and unload still interrupt the task, teardown interrupts a running task promptly, and cancellation is counted once. WIT change is documentation only. Verified on macOS with a 75 s task.

Co-authored-by: chaoes <[email protected]>

plugins/official/string-tools/dist/plugin.wasm.sources

@@ -1 +1 @@
-5e6457d34c922284779cdcc42455ed1df9ed8b9245793134be566dcd3c8aab93
+730d2bc7b15d2598840ec8668555f89cdf77b800c2ce21df7601880c57be6b2b