Set scopa targets to their traditional defaults

Partnership games go to 21: scopone scientifico (the tournament target)
and scopa a quattro, while two-player scopa keeps its usual 11. The scopa
package resolves the default from the player count and exposes a per
variant options_schema default, so the lobby creation form shows the
right value without frontend changes.

server/README.md

@@ -285,7 +285,7 @@ All endpoints except `/api/health`, `/api/docs`, `/api/openapi.json`,
 | Method | Path | Description |
 |---|---|---|
 | `GET` | `/api/game-types` | The games the platform can host (for the creation dropdown), each with its `options_schema` |
-| `POST` | `/api/games` | Create a lobby game. Optional body `{"game_type": "scopone_scientifico", "options": {"target_score": 11, "napola": true, "asso_pigliatutto": false}}`; scopa games use `{"game_type": "scopa"}` or `{"game_type": "scopa_a_quattro"}` with an optional `{"target_score": 11, "asso_pigliatutto": false}` (the asso pigliatutto rule makes it scopa d'assi); briscola games use `{"game_type": "briscola"}` or `{"game_type": "briscola_a_quattro"}` with an optional `{"target_score": 61}`, and briscola chiamata uses `{"game_type": "briscola_chiamata"}` with no options. Returns the lobby (`{id, join_code, players, seats_open, ...}`) |
+| `POST` | `/api/games` | Create a lobby game. Optional body `{"game_type": "scopone_scientifico", "options": {"target_score": 21, "napola": true, "asso_pigliatutto": false}}`; scopa games use `{"game_type": "scopa"}` (target default 11) or `{"game_type": "scopa_a_quattro"}` (target default 21) with an optional `{"target_score": 11, "asso_pigliatutto": false}` (the asso pigliatutto rule makes it scopa d'assi); briscola games use `{"game_type": "briscola"}` or `{"game_type": "briscola_a_quattro"}` with an optional `{"target_score": 61}`, and briscola chiamata uses `{"game_type": "briscola_chiamata"}` with no options. Returns the lobby (`{id, join_code, players, seats_open, ...}`) |
 | `POST` | `/api/games/join` | Join with `{"code": "ABC123"}`. The last player triggers the start and gets the game view back |
 | `GET` | `/api/games/preview?code=ABC123` | Pre-join summary of the lobby behind a code: game name/description, seated players, open seats and the engine-echoed options. `404` when the code is unknown |
 | `GET` | `/api/games/{id}` | Game snapshot. Seated players get the personalized view (own hand plus the join code); anyone else gets the read-only spectator view: table, scores, captured counts and scope, no hands and no join code |
@@ -420,9 +420,10 @@ rejected with an `illegal_move` error.
   empty. The capture never scores a scopa, but it counts as the last
   capture, and the mandatory equal-rank capture still applies when another
   ace is on the table.
-- The match ends when a team reaches the target score (default 11,
-  configurable per game via the `target_score` creation option) with a
-  clear lead; a tie at or above the target is broken by another hand.
+- The match ends when a team reaches the target score (default 21,
+  the traditional partnership target, configurable per game via the
+  `target_score` creation option) with a clear lead; a tie at or above
+  the target is broken by another hand.
 
 ### Scopa
 
@@ -447,9 +448,11 @@ rejected with an `illegal_move` error.
   the table is empty. The capture never scores a scopa, but it counts as
   the last capture, and the mandatory equal-rank capture still applies
   when another ace is on the table.
-- The match ends when a side reaches the target score (default 11,
-  configurable per game via the `target_score` creation option) with a
-  clear lead; a tie at or above the target is broken by another hand.
+- The match ends when a side reaches the target score (default 11 points
+  for two-player scopa and 21 for scopa a quattro, the traditional
+  partnership target; configurable per game via the `target_score`
+  creation option) with a clear lead; a tie at or above the target is
+  broken by another hand.
 - `scopa` is the classic two-player game; `scopa_a_quattro` seats four
   players in two fixed partnerships (seats 0/2 vs 1/3, partners
   opposite).