Add: add base fastapi backend

backend/.gitignore

@@ -0,0 +1,21 @@
+# Virtual environment
+.venv/
+venv/
+
+# Byte-compiled / optimized / DLL files
+__pycache__/
+*.py[cod]
+*$py.class
+
+# Secrets / env
+*.env
+
+# Translations
+*.mo
+*.pot
+
+# Jupyter Notebook
+.ipynb_checkpoints
+
+# Ruff formatter
+.ruff_cache/