Replace config.py with .env for Docker-standard configuration

Config was a Python file baked into the image or bind-mounted, requiring
a rebuild or manual file management for any settings change. Now uses
env_file in docker-compose with os.environ.get() calls, so config
changes only need a container restart. Also filters Gitea traffic from
LLM analysis to prevent false positive reconnaissance alerts on normal
repository browsing.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

.gitignore

@@ -0,0 +1,5 @@
+.env
+config.py
+__pycache__/
+data/
+cron.log