feat: add typed configuration loader with env support

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

app/config.py

@@ -0,0 +1,53 @@
+"""Application configuration loader.
+
+Reads environment variables (with .env file support) and provides
+a typed, validated Settings object used throughout the application.
+"""
+
+from functools import lru_cache
+from pathlib import Path
+
+from dotenv import load_dotenv
+from pydantic_settings import BaseSettings
+from pydantic_settings import SettingsConfigDict
+
+# Load .env file from project root
+_env_path = Path(__file__).resolve().parent.parent / ".env"
+load_dotenv(_env_path)
+
+
+class Settings(BaseSettings):
+    """Typed application settings loaded from environment variables.
+
+    Attributes:
+        admin_username: Admin login username (from ADMIN_USERNAME env var).
+        admin_password: Admin login password (from ADMIN_PASSWORD env var).
+        app_env: Runtime environment — 'development' or 'production'.
+        app_host: Host address to bind the server to.
+        app_port: Port number for the server.
+        app_log_level: Minimum log level for structlog output.
+        database_url: SQLite connection string.
+    """
+
+    admin_username: str
+    admin_password: str
+    app_env: str = "development"
+    app_host: str = "0.0.0.0"
+    app_port: int = 8000
+    app_log_level: str = "info"
+    database_url: str = "sqlite:///data/sneakyswole.db"
+
+    model_config = SettingsConfigDict(
+        env_file=".env",
+        env_file_encoding="utf-8",
+    )
+
+
+@lru_cache(maxsize=1)
+def get_settings() -> Settings:
+    """Return a cached Settings instance (singleton pattern).
+
+    Returns:
+        The application Settings object.
+    """
+    return Settings()