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.

web/src/model.rs

@@ -1125,7 +1125,7 @@ mod tests {
                 "properties": {
                     "target_score": {
                         "type": "integer", "minimum": 1, "maximum": 100,
-                        "default": 11,
+                        "default": 21,
                     },
                     "napola": {"type": "boolean", "default": true},
                     "asso_pigliatutto": {"type": "boolean", "default": false},
@@ -1146,7 +1146,7 @@ mod tests {
             target.kind,
             OptionKind::Integer { min: Some(1), max: Some(100) }
         ));
-        assert_eq!(json!(11), target.default);
+        assert_eq!(json!(21), target.default);
         assert_eq!(OptionKind::Boolean, by_key["napola"].kind);
         assert_eq!(json!(true), by_key["napola"].default);
         assert_eq!(OptionKind::Boolean, by_key["asso_pigliatutto"].kind);
@@ -1180,7 +1180,7 @@ mod tests {
     #[test]
     fn default_options_collect_schema_defaults() {
         let opts = scopone_game_type().default_options();
-        assert_eq!(Some(&json!(11)), opts.get("target_score"));
+        assert_eq!(Some(&json!(21)), opts.get("target_score"));
         assert_eq!(Some(&json!(true)), opts.get("napola"));
         assert_eq!(Some(&json!(false)), opts.get("asso_pigliatutto"));
     }