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.

web/Cargo.toml

@@ -1,8 +1,8 @@
 [package]
-name = "scopa-web"
+name = "tavolo-web"
 version = "0.1.0"
 edition = "2021"
-description = "Sycamore/WASM frontend for the scopone scientifico backend"
+description = "Sycamore/WASM frontend for the tavolo card-game platform"
 
 [dependencies]
 sycamore = "0.9"