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/config.json

@@ -2,7 +2,7 @@
   "interactiveLogin": true,
   "tokenCallbacks": [
     {
-      "issuerId": "scopa",
+      "issuerId": "tavolo",
       "tokenExpiry": 3600,
       "requestMappings": [
         {