Grading-path notification+email both lost on pool timeout (Class-A)

practica-actions.ts:674-700 (grading path) has the identical best-effort-post-commit shape as the create-path bug fixed in PLUTO-692, but also calls sendPracticaReviewedEmail inside the same try with its own second pool checkout. A pool-acquire timeout here loses a bell row AND an outbound email — this IS on the email-send path, so Class-A (audit design-ping pre-implementation, diff review pre-push, PTD after). Surfaced by coder-pluto-cc during PLUTO-692 investigation, 2026-08-11.