Add PreparedEdit::delete_pages_permanently: remove explicitly selected page
spaces and their section references in one transaction. Removed pages keep
their declarations with an empty manifest and the deleted-content flag; the
first survivor is promoted to level one, other levels and series identities
are retained, and no recycle-bin copy is written. Page placement and removal
share one writer; the removal-reference corpus seeds the page fuzz target.

Validation: 298 workspace tests including six deletion oracles against the
native removal references and twelve-client removal schedules; Clippy and
fuzz targets build. Native editing after a Rust removal is not yet verified;
offline replay of removal is deliberately not added pending the page-model
redesign in evidence/ROADMAP.md.

Assisted-by: claude-fable-5.1