chore: initial project setup with backend, frontend, and infrastructure

Add complete NexaPantry application structure including:
- Docker Compose configuration with PostgreSQL, Redis, FastAPI backend, worker, frontend and Caddy
- Environment configuration template with database, auth, and service settings
- GitHub Actions CI workflow for backend/frontend linting, testing, auditing and Docker builds
- AGPL-3.0 license and comprehensive README with setup, development, and security documentation
- Backend

backend/app/core/config.py

@@ -0,0 +1,34 @@
+from functools import lru_cache
+
+from pydantic import field_validator
+from pydantic_settings import BaseSettings, SettingsConfigDict
+
+
+class Settings(BaseSettings):
+    app_env: str = "production"
+    instance_url: str = "http://localhost"
+    frontend_origin: str = "http://localhost"
+    database_url: str = "postgresql+psycopg://nexapantry:nexapantry@localhost:5432/nexapantry"
+    redis_url: str | None = None
+    jwt_secret_key: str
+    settings_secret_key: str
+    cookie_secure: bool = True
+    cors_origins: list[str] = ["http://localhost"]
+    log_level: str = "INFO"
+    default_timezone: str = "Europe/Vienna"
+    daily_worker_interval_seconds: int = 300
+
+    model_config = SettingsConfigDict(env_file=".env", env_file_encoding="utf-8", extra="ignore")
+
+    @field_validator("cors_origins", mode="before")
+    @classmethod
+    def parse_origins(cls, value: str | list[str]) -> list[str]:
+        if isinstance(value, str):
+            return [origin.strip() for origin in value.split(",") if origin.strip()]
+        return value
+
+
+@lru_cache
+def get_settings() -> Settings:
+    return Settings()
+