Backend: Beleg-Analyse um Kaufdatum + Shop; Analyse-Endpoint

- guess_acquired_on (Kaufdatum) und guess_shop (bekannter Shop erkannt -> id;
  sonst Kandidatenname zum Anlegen) ergaenzt.
- Upload liefert zusaetzlich suggested_acquired_on / shop_id / shop_name.
- Neuer POST /items/analyze-document: analysiert einen Beleg OHNE zu speichern
  (zum Vorbefuellen beim Anlegen). Gemeinsamer Helfer _doc_suggestions.
- 6 neue Tests; Suite 150 gruen.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

backend/app/routers/items.py

@@ -24,6 +24,7 @@ from ..models import (
     User,
 )
 from ..schemas import (
+    DocumentSuggestions,
     ItemCreate,
     ItemDocumentUploadOut,
     ItemOut,
@@ -33,8 +34,10 @@ from ..schemas import (
 from ..services.items import generate_uid, item_to_out
 from ..services.warranty import (
     extract_pdf_text,
+    guess_acquired_on,
     guess_price_candidates,
     guess_price_cents,
+    guess_shop,
     guess_warranty_until,
 )
 
@@ -208,20 +211,8 @@ def _safe_filename(name: str | None) -> str:
     return cleaned[:255] or "beleg"
 
 
-@router.post(
-    "/items/{item_id}/documents",
-    response_model=ItemDocumentUploadOut,
-    status_code=status.HTTP_201_CREATED,
-)
-async def upload_item_document(
-    item_id: int,
-    file: UploadFile = File(...),
-    db: Session = Depends(get_db),
-    _: User = Depends(require_admin),
-) -> ItemDocumentUploadOut:
-    """Beleg (PDF oder Bild) hochladen. Bei PDF wird ein Garantieende vorgeschlagen."""
-    item = _item_or_404(db, item_id)
-    data = await file.read()
+def _read_document(file: UploadFile, data: bytes) -> str:
+    """Validiert Größe/Typ eines hochgeladenen Belegs und gibt den Content-Type."""
     if not data:
         raise HTTPException(status.HTTP_400_BAD_REQUEST, "Leere Datei")
     if len(data) > DOC_MAX_BYTES:
@@ -234,6 +225,43 @@ async def upload_item_document(
         raise HTTPException(
             status.HTTP_415_UNSUPPORTED_MEDIA_TYPE, "Nur PDF oder Bild erlaubt."
         )
+    return content_type
+
+
+def _doc_suggestions(
+    db: Session, data: bytes, content_type: str, item_acquired_on=None
+) -> DocumentSuggestions:
+    """Garantie, Preis, Kaufdatum und Shop aus einem PDF schätzen (Bilder: leer)."""
+    if content_type != "application/pdf":
+        return DocumentSuggestions()
+    text = extract_pdf_text(data)
+    shop_id, shop_name = guess_shop(text, [(s.id, s.name) for s in db.query(Shop).all()])
+    return DocumentSuggestions(
+        suggested_warranty_until=guess_warranty_until(text, acquired_on=item_acquired_on),
+        suggested_price_cents=guess_price_cents(text),
+        suggested_price_candidates=guess_price_candidates(text),
+        suggested_acquired_on=guess_acquired_on(text),
+        suggested_shop_id=shop_id,
+        suggested_shop_name=shop_name,
+    )
+
+
+@router.post(
+    "/items/{item_id}/documents",
+    response_model=ItemDocumentUploadOut,
+    status_code=status.HTTP_201_CREATED,
+)
+async def upload_item_document(
+    item_id: int,
+    file: UploadFile = File(...),
+    db: Session = Depends(get_db),
+    _: User = Depends(require_admin),
+) -> ItemDocumentUploadOut:
+    """Beleg (PDF oder Bild) hochladen. Bei PDF werden Garantie, Preis, Kaufdatum
+    und Shop vorgeschlagen."""
+    item = _item_or_404(db, item_id)
+    data = await file.read()
+    content_type = _read_document(file, data)
 
     doc = ItemDocument(
         item_id=item.id,
@@ -245,26 +273,28 @@ async def upload_item_document(
     db.commit()
     db.refresh(doc)
 
-    # Garantieende und Preis nur aus PDFs schätzen (Bilder haben keine Textebene).
-    warranty = price = None
-    candidates: list[int] = []
-    if content_type == "application/pdf":
-        text = extract_pdf_text(data)
-        warranty = guess_warranty_until(text, acquired_on=item.acquired_on)
-        price = guess_price_cents(text)
-        candidates = guess_price_candidates(text)
-
+    vorschlag = _doc_suggestions(db, data, content_type, item.acquired_on)
     return ItemDocumentUploadOut(
         id=doc.id,
         filename=doc.filename,
         content_type=doc.content_type,
         uploaded_at=doc.uploaded_at,
-        suggested_warranty_until=warranty,
-        suggested_price_cents=price,
-        suggested_price_candidates=candidates,
+        **vorschlag.model_dump(),
     )
 
 
+@router.post("/items/analyze-document", response_model=DocumentSuggestions)
+async def analyze_item_document(
+    file: UploadFile = File(...),
+    db: Session = Depends(get_db),
+    _: User = Depends(require_admin),
+) -> DocumentSuggestions:
+    """Beleg nur analysieren (nichts speichern) – zum Vorbefüllen beim Anlegen."""
+    data = await file.read()
+    content_type = _read_document(file, data)
+    return _doc_suggestions(db, data, content_type)
+
+
 @router.get("/items/{item_id}/documents/{doc_id}")
 def get_item_document(
     item_id: int,