Add briscola: classic two-player and briscola a quattro

New tavolo-briscola distribution implementing briscola on the platform:

- pure rules (state.py, engine.py): 3-card deals, a face-up trump that
  is the last card drawn, trump-first trick resolution (A > 3 > K > H >
  J > 7 > 6 > 5 > 4 > 2), 120 points per deal, 60-60 patta re-deals, a
  configurable target score (default 61), deal-end acknowledgements and
  turn auto-play;
- BriscolaEngine (briscola, 2 players) and BriscolaQuattroEngine
  (briscola_a_quattro, 4 players in fixed partnerships) adapters;
- registered in tavolo-app, packaged in the Docker image, documented.

Platform fixes surfaced by a two-player lobby:

- the websocket state and snapshot payloads now carry seats_open (they
  were only in the REST lobby payload), so lobbies with player counts
  other than four render correctly; seats_open is clamped at zero;
- the web client logs unparseable server messages instead of silently
  dropping them.

Web client: briscola table for both variants (stock, face-up trump,
trick, last-trick banner), deal summary modal and game-over overlay.

Tests: tavolo-briscola rules/adapter suites, app integration tests
(lobby, websocket play, turn timeout, deal-end acks, persistence), a
platform seats_open test and frontend model parsing tests.

web/src/pages/game.rs

@@ -6,11 +6,16 @@ use sycamore::prelude::*;
 use wasm_bindgen_futures::spawn_local;
 
 use crate::api;
+use crate::components::briscola::{deal_rows, deal_summary_modal};
 use crate::components::card::{card_back, card_img};
 use crate::components::copy::CopyButton;
 use crate::components::summary::{hand_summary_modal, summary_rows};
 use crate::components::toast::toast;
-use crate::model::{card_label, hand_sort_key, GameView, MoveView, PlayerView, Scores, ServerMessage};
+use crate::model::{
+    card_label, hand_sort_key, is_briscola, GameView, MoveView, PlayerView, Scores,
+    ServerMessage,
+};
+use crate::pages::briscola::briscola_table;
 use crate::ws::{self, GameSocket};
 
 fn send_play(socket: Signal<Option<GameSocket>>, card: String, capture: Option<Vec<String>>) {
@@ -20,7 +25,7 @@ fn send_play(socket: Signal<Option<GameSocket>>, card: String, capture: Option<V
 }
 
 /// The absolute, shareable URL of this game's page, for the clipboard.
-fn watch_link(id: &str) -> String {
+pub(crate) fn watch_link(id: &str) -> String {
     let origin = web_sys::window()
         .and_then(|w| w.location().origin().ok())
         .unwrap_or_default();
@@ -387,6 +392,10 @@ pub fn GamePage(id: String) -> View {
                     }
                 }
                 Some(g) if g.phase == "lobby" => view! { LobbyView(game=g) },
+                // Briscola has its own table view for both variants.
+                Some(g) if is_briscola(&g.game_type) => {
+                    briscola_table(g, on_hand_card, now)
+                }
                 // The live table is scopone-specific; other games get a
                 // fallback until they ship their own play view.
                 Some(g) if g.game_type == "scopone_scientifico" => {
@@ -401,6 +410,9 @@ pub fn GamePage(id: String) -> View {
                 Some(g) if g.phase == "hand_end" && g.game_type == "scopone_scientifico" => {
                     hand_summary_modal(g, socket, now)
                 }
+                Some(g) if g.phase == "hand_end" && is_briscola(&g.game_type) => {
+                    deal_summary_modal(g, socket, now)
+                }
                 _ => view! {},
             })
             (move || game_over_view(over.get_clone(), game.get_clone()))
@@ -715,11 +727,11 @@ fn capture_picker(
     }
 }
 
-/// End-of-match overlay (scopone's team score; other games render
-/// nothing until they ship their own play view).
+/// End-of-match overlay: the final hand/deal breakdown and the winner.
 fn game_over_view(over: Option<(Scores, Option<String>)>, game: Option<GameView>) -> View {
+    let briscola = game.as_ref().is_some_and(|g| is_briscola(&g.game_type));
     if let Some(g) = &game {
-        if g.game_type != "scopone_scientifico" {
+        if g.game_type != "scopone_scientifico" && !briscola {
             return view! {};
         }
     }
@@ -735,13 +747,19 @@ fn game_over_view(over: Option<(Scores, Option<String>)>, game: Option<GameView>
             let line = format!("Team {winner} wins {} – {}", scores.a, scores.b);
             // Spectators have no match history to look at.
             let spectator = game.as_ref().is_some_and(|g| g.spectator);
-            // Explain the final hand's scoring before the result.
-            let final_summary = game
-                .and_then(|g| g.last_hand)
-                .map(|s| {
-                    let rows = summary_rows(s);
-                    view! { (rows) }
-                });
+            // Explain the final hand's (scopone) or deal's (briscola)
+            // scoring before the result.
+            let final_summary: View = if briscola {
+                match game.as_ref().and_then(|g| g.last_deal.clone()) {
+                    Some(deal) => deal_rows(&deal),
+                    None => view! {},
+                }
+            } else {
+                match game.as_ref().and_then(|g| g.last_hand.clone()) {
+                    Some(hand) => summary_rows(hand),
+                    None => view! {},
+                }
+            };
             let my_matches = (!spectator).then(|| view! {
                 a(class="btn btn-outline-light", href="/history") { "My matches" }
             });