Better defaults for getting started

It would be desirable if someone getting started with Stork would be able to get an agent and a server running on the same machine with simple commands without any flags:

1. stork-tool db-create (hover for info)
2. stork-agent
3. stork-server

This is doable, except for a few defaults that could be improved.

Flag	Current default value	Suggested default value	Reasoning
STORK_AGENT_HOST	N/A	localhost	To have stork-agent started instead of complaining about missing flag.
STORK_AGENT_PORT	8080	8880 or any other	To not conflict with the default port for stork-server.
STORK_REST_STATIC_FILES_DIR	./webui/dist/stork or /usr/share/stork/www	../share/stork/www	Simpler logic. Less error-prone in case ./webui/dist/stork exists incidentally. Works for installations with custom paths. In case static files still need to be served from webui because it messes auto-reload or for some other reason, I think the logic could still be changed to ./webui/dist/stork or ../share/stork/www.