feat(v5.10.0): v5.4.0 + v5.5.0 features — backlinks, page/collection duplication, trash purge, version history, markdown import, embed/bookmark/video/audio blocks, cover & icon, OG metadata

- Migration v7: page_versions table + pages.cover_url/page_icon columns
- Trash service (purge_expired 30-day) + daily scheduler
- Board API: duplicate page, backlinks, versions (snapshot/list/restore), cover/icon upload, markdown/file import
- Collections API: duplicate collection (deep copy properties/views/pages/data sources)
- Export service: render embed/bookmark/video/audio in markdown/HTML/PDF/public
- Public page renderer: cover image + icon
- Editor: slash commands for media blocks, lightbox, version history UI, backlinks panel, cover/icon picker, import modal
- OG metadata endpoint for bookmark cards
- 386 tests passing

app/services/export.py

@@ -464,6 +464,11 @@ def _page_markdown_source(page: dict) -> str:
     return ""
 
 
+def markdown_to_blocks(md: str) -> list:
+    """Public wrapper around the GFM→blocks parser (used by page import)."""
+    return _md_to_blocks(md)
+
+
 # ═══════════════ Markdown ═══════════════
 
 def blocks_to_markdown(blocks: list) -> str:
@@ -508,6 +513,20 @@ def blocks_to_markdown(blocks: list) -> str:
             src = b.get("src") or ""
             alt = (b.get("alt") or "").strip() or "image"
             out.append(f"![{alt}]({src})")
+        elif t == "video":
+            out.append(f"[Video]({b.get('src') or ''})")
+        elif t == "audio":
+            out.append(f"[Audio]({b.get('src') or ''})")
+        elif t == "bookmark":
+            url = b.get("url") or b.get("src") or ""
+            title = (b.get("title") or "").strip()
+            out.append(f"[{title or url}]({url})" if title else url)
+        elif t == "embed":
+            url = b.get("src") or ""
+            if b.get("embed_type") in ("pdf", "download", None, ""):
+                out.append(f"[{url}]({url})" if url else "[embed]")
+            else:
+                out.append(f"[{url}]({url})" if url else "[embed]")
         elif t == "table":
             out.append(_table_to_markdown(b))
         else:
@@ -609,7 +628,54 @@ def blocks_to_html(blocks: list) -> str:
         elif t == "image":
             src = b.get("src") or ""
             alt = _text(b.get("alt"))
-            parts.append(f'<figure><img src="{src}" alt="{alt}"><figcaption>{alt}</figcaption></figure>')
+            parts.append(f'<figure><img src="{src}" alt="{alt}" class="fd-img" data-full="{src}"><figcaption>{alt}</figcaption></figure>')
+        elif t == "video":
+            src = b.get("src") or ""
+            if src:
+                parts.append(f'<video controls preload="metadata" style="max-width:100%;border-radius:8px;"><source src="{src}"></video>')
+        elif t == "audio":
+            src = b.get("src") or ""
+            if src:
+                parts.append(f'<audio controls preload="metadata" style="width:100%;"><source src="{src}"></audio>')
+        elif t == "bookmark":
+            url = b.get("url") or b.get("src") or ""
+            title = _text(b.get("title")) or url
+            desc = _text(b.get("description"))
+            img = b.get("image") or ""
+            site = _text(b.get("site_name")) or ""
+            img_html = f'<img src="{img}" alt="" style="width:120px;height:90px;object-fit:cover;border-radius:8px;flex-shrink:0;">' if img else ""
+            desc_html = f'<div style="font-size:13px;color:#57606a;margin-top:4px;">{desc}</div>' if desc else ""
+            site_html = f'<div style="font-size:11px;color:#8b949e;text-transform:uppercase;letter-spacing:.5px;margin-top:6px;">{site}</div>' if site else ""
+            parts.append(
+                f'<a href="{_text(url)}" target="_blank" rel="noopener noreferrer" style="text-decoration:none;color:inherit;">'
+                f'<div style="display:flex;gap:14px;align-items:center;border:1px solid #d8dee4;border-radius:10px;'
+                f'padding:14px 16px;margin:14px 0;background:#f9fafb;">'
+                f'<div style="flex:1;min-width:0;"><div style="font-weight:600;font-size:15px;">{title}</div>'
+                f'{desc_html}{site_html}</div>{img_html}</div></a>'
+            )
+        elif t == "embed":
+            url = b.get("src") or ""
+            emb = (b.get("embed_type") or "")
+            if emb in ("inline_dbs", "collection"):
+                parts.append(f'<div class="embed-note">[Embedded content]</div>')
+            elif emb == "download":
+                parts.append(f'<a href="{_text(url)}" download>⬇ {_text(b.get("file_name") or "Download")}</a>')
+            elif emb == "pdf" and url:
+                parts.append(f'<iframe src="{_text(url)}" style="width:100%;height:70vh;border:none;border-radius:8px;"></iframe>')
+            elif url:
+                from app.services.embeds import embed_src
+                src = embed_src(url) or url
+                height = 520
+                if b.get("height"):
+                    try:
+                        height = int(b["height"])
+                    except (ValueError, TypeError):
+                        pass
+                parts.append(
+                    f'<div style="position:relative;width:100%;height:{height}px;border-radius:8px;overflow:hidden;'
+                    f'background:#0a0a0a;"><iframe src="{src}" loading="lazy" frameborder="0" '
+                    f'style="position:absolute;inset:0;width:100%;height:100%;" allowfullscreen allow="autoplay; encrypted-media; picture-in-picture"></iframe></div>'
+                )
         elif t == "table":
             parts.append(_table_to_html(b))
         else: