feat: scaffold FastAPI app, config, and SQLite models

Co-authored-by: Cursor <cursoragent@cursor.com>

backend/app/models.py

@@ -0,0 +1,35 @@
+from datetime import datetime
+
+from sqlalchemy import Boolean, DateTime, Integer, String, Text
+from sqlalchemy.orm import Mapped, mapped_column
+
+from app.db import Base
+
+
+class Item(Base):
+    __tablename__ = "items"
+
+    id: Mapped[int] = mapped_column(primary_key=True)
+    slug: Mapped[str] = mapped_column(String(32), unique=True, index=True)
+    kind: Mapped[str] = mapped_column(String(16))  # text|file
+    title: Mapped[str] = mapped_column(String(255), default="")
+    body: Mapped[str | None] = mapped_column(Text, nullable=True)
+    file_name: Mapped[str | None] = mapped_column(String(512), nullable=True)
+    file_path: Mapped[str | None] = mapped_column(String(512), nullable=True)
+    mime: Mapped[str | None] = mapped_column(String(128), nullable=True)
+    size_bytes: Mapped[int | None] = mapped_column(Integer, nullable=True)
+    is_public: Mapped[bool] = mapped_column(Boolean, default=True)
+    burn_after_read: Mapped[bool] = mapped_column(Boolean, default=False)
+    expires_at: Mapped[datetime | None] = mapped_column(DateTime, nullable=True)
+    created_ip: Mapped[str] = mapped_column(String(64), default="")
+    created_at: Mapped[datetime] = mapped_column(DateTime, default=datetime.utcnow)
+    view_count: Mapped[int] = mapped_column(Integer, default=0)
+    burned: Mapped[bool] = mapped_column(Boolean, default=False)
+
+
+class BannedIP(Base):
+    __tablename__ = "banned_ips"
+
+    ip: Mapped[str] = mapped_column(String(64), primary_key=True)
+    reason: Mapped[str] = mapped_column(String(255), default="")
+    created_at: Mapped[datetime] = mapped_column(DateTime, default=datetime.utcnow)