chore: initial project setup with backend, frontend, CI/CD, and documentation

Add complete NexaFabric project structure including:
- FastAPI backend with SQLAlchemy models, JWT auth, RBAC, audit logging, and provider interfaces
- React + TypeScript frontend with Vite, Tailwind CSS, TanStack Query, and Zustand
- Docker Compose configuration for PostgreSQL, Redis, API, worker, frontend, and nginx
- GitHub Actions and GitLab CI workflows for testing, linting, building, and security scanning
- Environment

backend/app/core/config.py

@@ -0,0 +1,26 @@
+from functools import lru_cache
+
+from pydantic import AnyHttpUrl, Field
+from pydantic_settings import BaseSettings, SettingsConfigDict
+
+
+class Settings(BaseSettings):
+    model_config = SettingsConfigDict(env_file=".env", env_file_encoding="utf-8", extra="ignore")
+
+    project_name: str = "NexaFabric"
+    environment: str = "development"
+    api_host: str = "0.0.0.0"
+    api_port: int = 8000
+    database_url: str = "sqlite:///./nexafabric.db"
+    redis_url: str = "redis://localhost:6379/0"
+    jwt_secret: str = Field(default="dev-only-change-me")
+    jwt_access_token_minutes: int = 15
+    jwt_refresh_token_days: int = 14
+    token_encryption_key: str = "dev-only-change-me"
+    demo_admin_password: str = "ChangeMe_UseEnvInstead"
+    cors_origins: list[AnyHttpUrl] | list[str] = ["http://localhost:5173", "http://localhost:8080"]
+
+
+@lru_cache
+def get_settings() -> Settings:
+    return Settings()