Enhance API and configuration for Telegram miniapp

- Added support for CORS origins and a new environment variable for miniapp access control.
- Implemented date validation for API requests to ensure correct date formats.
- Updated FastAPI app to allow access without Telegram initData for local development.
- Enhanced error handling and logging for better debugging.
- Added tests for API functionality and Telegram initData validation.
- Updated README with new environment variable details and testing instructions.
- Modified Docker and Git ignore files to include additional directories and files.

conftest.py

@@ -0,0 +1,6 @@
+"""Pytest configuration. Set BOT_TOKEN so config module can be imported."""
+import os
+
+# Set before any project code imports config (which requires BOT_TOKEN).
+if not os.environ.get("BOT_TOKEN"):
+    os.environ["BOT_TOKEN"] = "test-token-for-pytest"