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/config.py

@@ -0,0 +1,120 @@
+"""Configuration management for Sneaky Klaus application.
+
+This module defines configuration classes for different environments
+(development, production, testing) with environment variable support.
+"""
+
+import os
+from datetime import timedelta
+from pathlib import Path
+
+
+class Config:
+    """Base configuration class with common settings."""
+
+    # Base paths
+    BASE_DIR = Path(__file__).parent.parent
+    DATA_DIR = BASE_DIR / "data"
+
+    # Security
+    SECRET_KEY = os.environ.get("SECRET_KEY") or "dev-secret-key-change-in-production"
+
+    # Database
+    SQLALCHEMY_DATABASE_URI = os.environ.get(
+        "DATABASE_URL", f"sqlite:///{DATA_DIR / 'sneaky-klaus.db'}"
+    )
+    SQLALCHEMY_TRACK_MODIFICATIONS = False
+
+    # Session management
+    SESSION_TYPE = "sqlalchemy"
+    SESSION_PERMANENT = True
+    SESSION_USE_SIGNER = True
+    SESSION_KEY_PREFIX = "sk:"
+    PERMANENT_SESSION_LIFETIME = timedelta(days=7)
+    SESSION_COOKIE_SECURE = True  # HTTPS only
+    SESSION_COOKIE_HTTPONLY = True
+    SESSION_COOKIE_SAMESITE = "Lax"
+
+    # Flask-WTF CSRF Protection
+    WTF_CSRF_ENABLED = True
+    WTF_CSRF_TIME_LIMIT = None  # No time limit for CSRF tokens
+
+    # Email service (Resend)
+    RESEND_API_KEY = os.environ.get("RESEND_API_KEY")
+
+    # Application URLs
+    APP_URL = os.environ.get("APP_URL", "http://localhost:5000")
+
+    # Timezone
+    TIMEZONE = os.environ.get("TZ", "UTC")
+
+    # Password requirements
+    MIN_PASSWORD_LENGTH = 12
+
+
+class DevelopmentConfig(Config):
+    """Development environment configuration."""
+
+    DEBUG = True
+    TESTING = False
+    SESSION_COOKIE_SECURE = False  # Allow HTTP in development
+    SQLALCHEMY_ECHO = True  # Log SQL queries
+
+
+class ProductionConfig(Config):
+    """Production environment configuration."""
+
+    DEBUG = False
+    TESTING = False
+
+    # Ensure critical environment variables are set
+    @classmethod
+    def validate(cls):
+        """Validate that required production configuration is present."""
+        required_vars = ["SECRET_KEY", "RESEND_API_KEY", "APP_URL"]
+        missing_vars = [var for var in required_vars if not os.environ.get(var)]
+        if missing_vars:
+            raise ValueError(
+                f"Missing required environment variables: {', '.join(missing_vars)}"
+            )
+
+
+class TestConfig(Config):
+    """Test environment configuration."""
+
+    TESTING = True
+    DEBUG = True
+    SESSION_COOKIE_SECURE = False
+
+    # Use in-memory database for tests
+    SQLALCHEMY_DATABASE_URI = "sqlite:///:memory:"
+
+    # Disable CSRF for easier testing
+    WTF_CSRF_ENABLED = False
+
+    # Use a predictable secret key for tests
+    SECRET_KEY = "test-secret-key"
+
+
+# Configuration dictionary for easy access
+config = {
+    "development": DevelopmentConfig,
+    "production": ProductionConfig,
+    "testing": TestConfig,
+    "default": DevelopmentConfig,
+}
+
+
+def get_config(env: str | None = None) -> type[Config]:
+    """Get configuration class based on environment.
+
+    Args:
+        env: Environment name (development, production, testing).
+             If None, uses FLASK_ENV environment variable.
+
+    Returns:
+        Configuration class for the specified environment.
+    """
+    if env is None:
+        env = os.environ.get("FLASK_ENV", "development")
+    return config.get(env, config["default"])