feat(backend): add FastAPI backend — procurement, inventory domain, Casdoor auth, PM arrival endpoints

backend/app/models/files.py

@@ -0,0 +1,52 @@
+"""ORM model for invoice / proforma attachments (table `quote_attachments`).
+
+File bytes live in MinIO object storage; this table is the metadata record
+(``object_key`` points at the object inside the PROCUREMENT_MINIO_BUCKET).
+Multiple attachments per quote per kind are allowed (multi-file contract,
+no unique constraint on (quote_id, kind)).
+"""
+import uuid
+from datetime import datetime
+
+from sqlalchemy import BigInteger, CheckConstraint, DateTime, ForeignKey, Text, func
+from sqlalchemy.orm import Mapped, mapped_column, relationship
+
+from app.db.base import Base
+from app.models.catalog import _timestamptz, _uuid_pk
+from app.utils.serialization import to_iso
+
+
+class QuoteAttachment(Base):
+    __tablename__ = "quote_attachments"
+    __mapper_args__ = {"eager_defaults": True}  # fetch onupdate=func.now() via RETURNING
+    __table_args__ = (
+        CheckConstraint("kind IN ('invoice', 'proforma')", name="ck_quote_attachments_kind"),
+    )
+
+    id: Mapped[uuid.UUID] = _uuid_pk()
+    quote_id: Mapped[uuid.UUID] = mapped_column(ForeignKey("quotes.id", ondelete="CASCADE"), nullable=False)
+    kind: Mapped[str] = mapped_column(Text, nullable=False)  # "invoice" | "proforma"
+    file_name: Mapped[str] = mapped_column(Text, nullable=False)
+    mime_type: Mapped[str] = mapped_column(Text, nullable=False)
+    size_bytes: Mapped[int] = mapped_column(BigInteger, nullable=False)
+    object_key: Mapped[str] = mapped_column(Text, nullable=False)  # MinIO key inside the bucket
+    uploaded_at: Mapped[datetime] = mapped_column(
+        DateTime(timezone=True), nullable=False, server_default=func.now()
+    )
+    created_at: Mapped[datetime] = _timestamptz()
+    updated_at: Mapped[datetime] = mapped_column(
+        DateTime(timezone=True), nullable=False, server_default=func.now(), onupdate=func.now()
+    )
+
+    quote: Mapped["Quote"] = relationship(lazy="raise")
+
+    def to_dict(self) -> dict:
+        return {
+            "id": str(self.id),
+            "quote_id": str(self.quote_id),
+            "kind": self.kind,
+            "file_name": self.file_name,
+            "mime_type": self.mime_type,
+            "size_bytes": self.size_bytes,
+            "uploaded_at": to_iso(self.uploaded_at),
+        }