Docker HTTPS by default, smoke test improvements

Docker:
- HTTPS enabled by default (generates self-signed cert)
- Added docker-entrypoint.sh for SSL cert generation
- Gunicorn now starts with --certfile/--keyfile when HTTPS enabled
- Install curl/openssl in web container for healthcheck and certs
- Updated docs to reflect HTTPS default

Smoke Test:
- Moved from rpi/ to scripts/ (works for Pi, Docker, and dev)
- Updated header and examples
- Added to .gitignore exceptions

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

README.md

@@ -105,12 +105,15 @@ ruff check src/ tests/ frontends/
 ## Docker
 
 ```bash
-# Quick start
+# Quick start (HTTPS enabled by default)
 docker-compose up -d
 
 # Access
-# Web UI:   http://localhost:5000
+# Web UI:   https://localhost:5000  (self-signed cert)
 # REST API: http://localhost:8000
+
+# Disable HTTPS if needed:
+STEGASOO_HTTPS_ENABLED=false docker-compose up -d
 ```
 
 See [DOCKER.md](DOCKER.md) for full documentation.