Rename the app from scopa to tavolo

The platform now hosts multiple card games, with scopone scientifico as
the first one. Rename the brand wherever it is not a game rule:

- move the Python package to server/src/tavolo and update imports
- rename the Postgres database/user, OIDC issuer path, client id and
  Redis key prefixes to tavolo (clean break: existing pgdata volumes and
  live games are not migrated)
- rename the Cargo package to tavolo-web and set the page title to Tavolo
- update docs and the Docker image path to woggioni/tavolo

The scopa game term (clearing the table) in the engine, state and web UI
is intentionally left untouched.

server/dev/mockoauth/Dockerfile

@@ -1,4 +1,4 @@
-# Dev OIDC provider: navikt/mock-oauth2-server with the scopa test
+# Dev OIDC provider: navikt/mock-oauth2-server with the tavolo test
 # configuration (four ready-made players) baked in. The config is
 # COPYed instead of bind-mounted so this also works against containerized
 # (e.g. rootless/DinD) docker daemons that cannot see the host workspace.