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/tests/__init__.py

@@ -1,7 +1,7 @@
 """Test package init.
 
 Sets environment overrides BEFORE any test module imports
-:mod:`scopa.app` (which evaluates :data:`scopa.config.settings`
+:mod:`tavolo.app` (which evaluates :data:`tavolo.config.settings`
 at import time). Works under both ``python -m unittest discover`` and
 ``pytest``; conftest.py mirrors this for pytest-only collection.
 """
@@ -10,8 +10,8 @@ from __future__ import annotations
 import os
 
 os.environ.setdefault("DATABASE_URL", "sqlite://:memory:")
-os.environ.setdefault("OIDC_ISSUER", "http://localhost:8180/scopa")
-os.environ.setdefault("OIDC_CLIENT_ID", "scopa")
+os.environ.setdefault("OIDC_ISSUER", "http://localhost:8180/tavolo")
+os.environ.setdefault("OIDC_CLIENT_ID", "tavolo")
 os.environ.setdefault("OIDC_REDIRECT_URI", "http://localhost:8080/auth/callback")
 # Unset REDIS_URL: sessions and live games use the in-memory fallbacks.
 os.environ.pop("REDIS_URL", None)