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.

README.md

@@ -1,7 +1,7 @@
-# scopa
+# tavolo
 
-Multiplayer **scopone scientifico** — the four-player, fixed-partnership
-Italian card game — as a web application:
+A platform for multiplayer card games. The first game is **scopone
+scientifico** — the four-player, fixed-partnership Italian card game:
 
 - **`server/`** — backend: Python + [kaya](https://github.com/woggioni/kaya)
   framework, OIDC login, live games in Redis, match statistics in Postgres.
@@ -22,7 +22,7 @@ Postgres, Redis, a mock OIDC provider (test users `alice`, `bob`, `carol`,
 frontend and API — listens on `http://127.0.0.1:8080`.
 
 Because both the browser and the app talk to the OIDC issuer at
-`http://mockoauth:8180/scopa`, add a host entry once:
+`http://mockoauth:8180/tavolo`, add a host entry once:
 
 ```sh
 echo "127.0.0.1 mockoauth" | sudo tee -a /etc/hosts
@@ -71,7 +71,7 @@ run the backend with:
 ```sh
 OIDC_POST_LOGIN_REDIRECT=http://localhost:8000/ \
 OIDC_POST_LOGOUT_REDIRECT=http://localhost:8000/ \
-  .venv/bin/granian --host 127.0.0.1 --port 8080 scopa.app:app
+  .venv/bin/granian --host 127.0.0.1 --port 8080 tavolo.app:app
 ```
 
 Card images are committed under `web/assets/cards/`; `web/fetch-cards.sh`