backend: add push token API and FCM delivery pipeline

app/notifications/models.py

@@ -1,6 +1,6 @@
 from datetime import datetime
 
-from sqlalchemy import DateTime, String, func
+from sqlalchemy import DateTime, ForeignKey, String, UniqueConstraint, func
 from sqlalchemy.orm import Mapped, mapped_column
 
 from app.database.base import Base
@@ -14,3 +14,22 @@ class NotificationLog(Base):
     event_type: Mapped[str] = mapped_column(String(64), index=True)
     payload: Mapped[str] = mapped_column(String(1024))
     created_at: Mapped[datetime] = mapped_column(DateTime(timezone=True), server_default=func.now(), nullable=False)
+
+
+class PushDeviceToken(Base):
+    __tablename__ = "push_device_tokens"
+    __table_args__ = (UniqueConstraint("user_id", "platform", "token", name="uq_push_device_tokens_user_platform_token"),)
+
+    id: Mapped[int] = mapped_column(primary_key=True, index=True)
+    user_id: Mapped[int] = mapped_column(ForeignKey("users.id", ondelete="CASCADE"), nullable=False, index=True)
+    platform: Mapped[str] = mapped_column(String(16), nullable=False, index=True)
+    token: Mapped[str] = mapped_column(String(512), nullable=False)
+    device_id: Mapped[str | None] = mapped_column(String(128), nullable=True)
+    app_version: Mapped[str | None] = mapped_column(String(64), nullable=True)
+    created_at: Mapped[datetime] = mapped_column(DateTime(timezone=True), server_default=func.now(), nullable=False)
+    updated_at: Mapped[datetime] = mapped_column(
+        DateTime(timezone=True),
+        server_default=func.now(),
+        onupdate=func.now(),
+        nullable=False,
+    )