plastic-roadmap-continuing

# Roadmap Continuing - resume the mid-flight roadmap `plastic-roadmap-continuing` is the roadmap route of `plastic-continuing`. It finds the tier's mid-flight roadmap, presents its state, then asks the user how to proceed, exactly once. Before intent 158a1 there was no automated way to do this: the `171` (consistency-dividend) roadmap handoff had to be resumed by hand, carried as a free-prose note in `171`'s own `## Insights`. This skill closes that gap. ## Find the mid-flight roadmap 1. Determine the tier (project vs. global) and enumerate that tier's live `roadmaps/*.md` (exclude `roadmaps/archived/`). Read via Read/glob, or `plastic-roadmap`'s Read/consume verb. See `plastic-roadmap`'s `references/file-format.md` for the file grammar; do not duplicate it here. 2. For each candidate, also read its paired ledger `roadmaps/<slug>.savepoint.md` when present (see `plastic-roadmap`'s `references/file-format.md#savepoint-ledger`): its last line(s) are a cheaper, precise last-event signal (for example `dispatched 134` or `merged 172`), read alongside the existing `## Batches` (or legacy `## Waves`) / `## Log` judgment. The ledger is read-only here, a derived signal, never a new status field; INDEX.md stays the sole status writer. 3. Rank liveness by calling the shared reader in which mode (one implementation across the auto loop and this skill): ```bash ruby ~/.plastic/scripts/roadmap-next --roadmaps-dir <tier>/roadmaps --which ``` Read `s...