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/importers/pdf.py

@@ -0,0 +1,94 @@
+"""FlowDeck — PDF importer (v5.6.0, Phase 3).
+
+Best-effort text + image extraction from a PDF into a FlowDeck page (fidelity
+depends on the source PDF; scanned documents have no text layer).
+"""
+from __future__ import annotations
+
+import io
+import re
+from pathlib import Path
+
+from app.services.importers.base import (
+    ImportAttachment,
+    Importer,
+    ImportPage,
+    ImportResult,
+    register_importer,
+)
+
+_MIME = {".png": "image/png", ".jpg": "image/jpeg", ".jpeg": "image/jpeg",
+         ".gif": "image/gif", ".webp": "image/webp", ".bmp": "image/bmp",
+         ".tiff": "image/tiff", ".tif": "image/tiff"}
+
+
+@register_importer
+class PdfImporter(Importer):
+    source_id = "pdf"
+    label = "PDF"
+    description = "Extraction texte + images d'un PDF (fidélité limitée)."
+    extensions = (".pdf",)
+    order = 37
+
+    def detect(self, filename: str, data: bytes) -> bool:
+        return filename.lower().endswith(".pdf")
+
+    def parse(self, filename: str, data: bytes) -> ImportResult:
+        result = ImportResult(source=self.source_id)
+        try:
+            from pypdf import PdfReader
+        except ImportError:
+            result.warn("pypdf n'est pas installé : import PDF indisponible")
+            return result.finalize()
+        try:
+            reader = PdfReader(io.BytesIO(data))
+        except Exception as exc:  # noqa: BLE001
+            result.warn(f"PDF illisible : {exc}")
+            return result.finalize()
+
+        chunks: list[str] = []
+        empty_pages = 0
+        for index, page in enumerate(reader.pages, start=1):
+            try:
+                text = (page.extract_text() or "").strip()
+            except Exception:  # noqa: BLE001
+                text = ""
+            if text:
+                if len(reader.pages) > 1:
+                    chunks.append(f"## Page {index}\n\n{text}")
+                else:
+                    chunks.append(text)
+            else:
+                empty_pages += 1
+            chunks.extend(self._page_images(page, index, result))
+
+        if empty_pages:
+            result.warn(f"{empty_pages} page(s) sans couche texte (document scanné ?)")
+        markdown = re.sub(r"\n{3,}", "\n\n", "\n\n".join(chunks)).strip()
+        title = Path(filename).stem or "Document"
+        result.pages.append(ImportPage(
+            title=title, markdown=markdown, source_path=filename, external_id=filename,
+        ))
+        return result.finalize()
+
+    def _page_images(self, page, index: int, result: ImportResult) -> list[str]:
+        images: list[str] = []
+        try:
+            page_images = list(page.images)
+        except Exception:  # noqa: BLE001
+            return images
+        for i, image in enumerate(page_images, start=1):
+            name = getattr(image, "name", "") or f"page{index}_img{i}.png"
+            name = Path(name).name
+            try:
+                payload = image.data
+            except Exception:  # noqa: BLE001
+                continue
+            if not payload:
+                continue
+            result.attachments.append(ImportAttachment(
+                source_path=f"page{index}/{name}", filename=name, data=payload,
+                mime=_MIME.get(Path(name).suffix.lower(), "application/octet-stream"),
+            ))
+            images.append(f"![{name}]({name})")
+        return images