Add admin account with user management endpoints

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

backend/app/models/user.py

@@ -1,6 +1,6 @@
 from datetime import datetime
 from typing import Optional
-from sqlalchemy import String, DateTime, func
+from sqlalchemy import String, DateTime, Boolean, func
 from sqlalchemy.orm import Mapped, mapped_column, relationship
 
 from app.database import Base
@@ -14,6 +14,8 @@ class User(Base):
     password_hash: Mapped[str] = mapped_column(String(255), nullable=False)
     display_name: Mapped[Optional[str]] = mapped_column(String(100))
     timezone: Mapped[str] = mapped_column(String(50), default="UTC")
+    is_admin: Mapped[bool] = mapped_column(Boolean, default=False, nullable=False)
+    is_disabled: Mapped[bool] = mapped_column(Boolean, default=False, nullable=False)
     created_at: Mapped[datetime] = mapped_column(DateTime, server_default=func.now())
 
     entries: Mapped[list["Entry"]] = relationship("Entry", back_populates="user", cascade="all, delete-orphan")