docrot v1.5.2 — triple-newline pairing edge closed

Residual edge in the v1.5.1 paragraph-local inline-code pairing, found while re-reviewing the fix itself: a content part starting with a single newline (triple-newline sequences) was misrouted as a blank-line separator and skipped pairing — the phantom-ref class survived in that corner (reproduced with a fixture, leaked p.png). Separator detection now requires a full blank-line match. Suite 87 green. The running 300-repo v7 rescan is being restarted under this release so the published v7 datasets carry the fully closed class.