TASK-047: persist unworked review notes (0 critical, 6 major, 27 minor)

Snapshot of the validation-loop findings deferred from this task. The 6
major items (offset accounting under multipart `pp`, repeated hook gate
expression, switch-arm duplication in hook_handle::remove, snapshot
helper duplication, curl helper duplication in tests, and the missing
fast-empty path in fire_short_circuit_hooks_for_phase) are candidates
for a sweep alongside TASK-048..051, where the same patterns repeat.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: etr