chore: initial project setup

Initialize Sneaky Klaus project with:
- uv package management and pyproject.toml
- Flask application structure (app.py, config.py)
- SQLAlchemy models for Admin and Exchange
- Alembic database migrations
- Pre-commit hooks configuration
- Development tooling (pytest, ruff, mypy)

Initial structure follows design documents in docs/:
- src/app.py: Application factory with Flask extensions
- src/config.py: Environment-based configuration
- src/models/: Admin and Exchange models
- migrations/: Alembic migration setup

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

src/models/admin.py

@@ -0,0 +1,48 @@
+"""Admin model for Sneaky Klaus.
+
+The Admin model represents the single administrator account
+for the entire installation.
+"""
+
+from datetime import datetime
+
+from sqlalchemy import DateTime, String
+from sqlalchemy.orm import Mapped, mapped_column
+
+from src.app import db
+
+
+class Admin(db.Model):  # type: ignore[name-defined]
+    """Administrator user model.
+
+    Represents the single admin account for the entire Sneaky Klaus installation.
+    Only one admin should exist per deployment.
+
+    Attributes:
+        id: Auto-increment primary key.
+        email: Admin email address (unique, indexed).
+        password_hash: bcrypt password hash.
+        created_at: Account creation timestamp.
+        updated_at: Last update timestamp.
+    """
+
+    __tablename__ = "admin"
+
+    id: Mapped[int] = mapped_column(primary_key=True)
+    email: Mapped[str] = mapped_column(
+        String(255), unique=True, nullable=False, index=True
+    )
+    password_hash: Mapped[str] = mapped_column(String(255), nullable=False)
+    created_at: Mapped[datetime] = mapped_column(
+        DateTime, nullable=False, default=datetime.utcnow
+    )
+    updated_at: Mapped[datetime] = mapped_column(
+        DateTime,
+        nullable=False,
+        default=datetime.utcnow,
+        onupdate=datetime.utcnow,
+    )
+
+    def __repr__(self) -> str:
+        """String representation of Admin instance."""
+        return f"<Admin {self.email}>"