feat: Initialize FastAPI application with Azure authentication and transaction management

- Added .env.example for environment variable configuration.
- Created app initialization files and core settings management.
- Implemented API routers for reporting and transaction endpoints.
- Developed transaction management service with CRUD operations.
- Integrated Azure OAuth for user authentication.
- Designed dashboard view with transaction filtering and display.
- Added Swagger UI documentation with custom dark theme.
- Created static and template files for frontend styling and layout.

app/core/settings.py

@@ -0,0 +1,26 @@
+from functools import lru_cache
+from os import getenv
+from pathlib import Path
+
+from dotenv import load_dotenv
+
+
+PROJECT_ROOT = Path(__file__).resolve().parents[2]
+load_dotenv(PROJECT_ROOT / ".env")
+
+
+class Settings:
+    def __init__(self) -> None:
+        self.session_secret_key = getenv("SESSION_SECRET_KEY", "change-me-in-production")
+        self.azure_tenant_id = getenv("AZURE_TENANT_ID")
+        self.azure_client_id = getenv("AZURE_CLIENT_ID")
+        self.azure_client_secret = getenv("AZURE_CLIENT_SECRET")
+
+    @property
+    def azure_configured(self) -> bool:
+        return bool(self.azure_tenant_id and self.azure_client_id and self.azure_client_secret)
+
+
+@lru_cache
+def get_settings() -> Settings:
+    return Settings()