7abce93543
After merging develop, git-sync's markdown converter still predated two editor features and silently dropped them on every sync: - Spoiler mark (#259): had no schema entry, so `<span data-spoiler>` from the canonical lossless form re-parsed as plain text and the mark was lost. Register a Spoiler mark mirroring @docmost/editor-ext + the MCP schema, and emit `<span data-spoiler="true">…</span>` on PM->MD. - Image caption (#221): the converter assumed no caption attribute existed (the branch was dead). The image schema now carries a plain-text caption (data-caption); register it and route a captioned image through the raw <img> form (same lossless convention as the other Docmost image attrs). Caption-less images keep the lighter `` form. Both survive PM->MD->PM unchanged; raw `<span data-spoiler>` / `<img data-caption>` in incoming markdown parse back. New round-trip tests in markdown-roundtrip-spoiler-caption.test.ts; schema-surface snapshot updated. Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>