add url handling

[ModischFabrications]

• reroute unknown paths back to "/"
• offer version on "/version"
• offer debug stuff on "/debug"

plaintext is useful for healthchecks, won't need to build the site.

[ModischFabrications]

Easier with Caddy now, just remember to remap paths to /api

[ModischFabrications]

https://caddy.community/t/remove-path-prefix-on-reverse-proxy/14325

Caddyfile should contain a "handle" block that takes in /api/* for all calls to cutsolver.

Remember to change URL in docker compose as well!