Remove preload_app: incompatible with eventlet on PyPy

eventlet monkey-patching fails when the app is preloaded, as modules
are already imported before workers can patch them.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: vthorsteinsson

config/gunicorn_config.py

@@ -8,7 +8,7 @@
 workers = 4
 threads = 2
 timeout = 120
-preload_app = True
+# Note: preload_app is not compatible with eventlet on PyPy
 max_requests = 1000
 max_requests_jitter = 50