fix: security and reliability improvements

- Switch HTTPServer to ThreadingHTTPServer (concurrent request handling)
- Replace SHA-256 password hashing with bcrypt (auth.py, database.py)
- Add bcrypt to Dockerfile
- Move qBittorrent env vars to config.py
- Move _booklore_token state out of config into booklore.py
- Remove dead fitness_token variable in command.py
- Fix OpenAI call to use default SSL context instead of no-verify ctx
- Log swallowed budget fetch error in dashboard.py

gateway/Dockerfile

@@ -1,5 +1,6 @@
 FROM python:3.12-slim
 WORKDIR /app
+RUN pip install bcrypt
 COPY server.py config.py database.py sessions.py proxy.py responses.py auth.py dashboard.py command.py ./
 COPY integrations/ ./integrations/
 EXPOSE 8100