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.

webapp/style.css

@@ -166,6 +166,12 @@ body {
   font-weight: 600;
 }
 
+.access-denied .debug {
+  font-size: 0.75rem;
+  margin-top: 12px;
+  word-break: break-all;
+}
+
 .access-denied[hidden] {
   display: none !important;
 }