feat: add one-click deploy script + project optimization

- deploy.sh: one-click deployment (squid + venv + pip + gunicorn + systemd)
- gunicorn_config.py: unified gunicorn config with env var overrides
- .env.example: env var template for SECRET_KEY, port, workers, security
- wsgi.py: create all runtime dirs (uploads, ssl_certs); optional dotenv loading
- requirements.txt: add python-dotenv + cryptography
- .gitignore: cover runtime dirs, .env, pyc files

requirements.txt

@@ -3,6 +3,8 @@ Flask-SQLAlchemy==3.1.1
 SQLAlchemy==2.0.30
 Werkzeug==3.0.3
 gunicorn==22.0.0
-# P3-3: WebSSH terminal
+python-dotenv>=1.0.0
 paramiko>=2.10.0
 flask-sock>=0.7.0
+# TLS cert management / ssl_certs module
+cryptography>=41.0.0