feat(import): v5.6.0 unified data import (phases 0-5)

- unified importer framework (app/services/importers/): normalized model,
  registry, common pipeline (hierarchy, attachments, collections, dedup),
  async jobs, dry-run preview, column->type mapping
- Phase 1: Obsidian, Notion, Logseq/Roam, HTML (Apple Notes/Bear/Ulysses/
  OneNote), Google Keep, generic Markdown
- Phase 2: typed CSV/TSV, Excel (openpyxl), generic JSON
- Phase 3: Word .docx (python-docx), PDF (pypdf), HTML folders
- Phase 4: Raindrop, Pocket, Readwise, Shaarli, Netscape bookmarks, .ics,
  OPML, Standard Notes, Gitea/GitHub issues (+labels/milestones)
- Phase 5: incremental re-sync (skip/update/duplicate), partial-error resume,
  forge repo files, URL web clipper (SSRF guard), batch multi-file + UI queue,
  Notion relation resolution, exportable JSON reports
- /import wizard, API /api/import/*, migration 9 (import_items, import_jobs)
- fix: property values stored by property id (correct DB view rendering)
- deps: openpyxl, beautifulsoup4, PyYAML, python-docx, pypdf
- 43 import tests; full suite 491 green; ruff clean
- bump version 5.11.5

app/services/export.py

@@ -390,6 +390,20 @@ def _md_to_blocks(md: str) -> list:
             blocks.append({"type": "divider", "content": ""})
             i += 1
             continue
+        if re.match(r"^\s*[-*+]\s+\[[ xX]\]\s+", line):
+            flush_para()
+            while i < n:
+                s = lines[i].strip()
+                m2 = re.match(r"^[-*+]\s+\[([ xX])\]\s+(.*)$", s)
+                if not m2:
+                    break
+                blocks.append({
+                    "type": "to_do",
+                    "content": m2.group(2).strip(),
+                    "checked": m2.group(1).lower() == "x",
+                })
+                i += 1
+            continue
         if re.match(r"^\s*[-*+]\s+", line):
             flush_para()
             while i < n:
@@ -410,21 +424,6 @@ def _md_to_blocks(md: str) -> list:
                 blocks.append({"type": "numbered_list", "content": m2.group(1).strip()})
                 i += 1
             continue
-        mtodo = re.match(r"^\s*[-*+]\s+\[([ xX])\]\s+(.*)$", stripped)
-        if mtodo:
-            flush_para()
-            while i < n:
-                s = lines[i].strip()
-                m2 = re.match(r"^[-*+]\s+\[([ xX])\]\s+(.*)$", s)
-                if not m2:
-                    break
-                blocks.append({
-                    "type": "to_do",
-                    "content": m2.group(2).strip(),
-                    "checked": m2.group(1).lower() == "x",
-                })
-                i += 1
-            continue
         mq = re.match(r"^>\s?(.*)$", stripped)
         if mq and line == stripped:
             flush_para()