Bug-fix release: multi-sheet TOC persistence.
POST /_/:room with text/csv was executed as a raw command batch (a silent no-op), so the worker-served multi-sheet UI (/=:room) never persisted its table of contents — sheets vanished from the tab bar on reload. CSV bodies now convert through the shared SheetJS import path into a loadclipboard command and reuse the legacy paste enrichment: paste A2 all on an empty room, appending after the last row otherwise, with ?row=N still inserting a row first. The 202 response echoes the enriched command array so multi-sheet clients (and HackFoldr) recover the persisted row number. Oversized CSV imports return 413; a cell-less CSV is a 202 no-op. XLSX/ODS POST behavior is unchanged.
Covered by unit, Durable Object round-trip, pinned legacy oracle, and Playwright lifecycle tests. See Changes.txt for details.