Offer a Continue link for ongoing games in the lobby

A player who accidentally closes the game page can now get back to it
from the lobby.

Backend:
- GameStore.list_ongoing() returns live unfinished sessions (newest
  first), skipping expired keys and finished matches;
- GET /api/me/games lists the games the caller is seated in, with the
  game name/description, players, open seats and your seat (no join
  code);
- store, platform route and app integration tests.

Frontend:
- MyGame/MyGamesPage model plus api::my_games();
- the lobby shows a "Your games" card with phase, seats, players and a
  Continue button linking to /game/<id>; hidden when empty or logged
  out.

web/src/pages/lobby.rs

@@ -16,7 +16,7 @@ use crate::components::card::card_back;
 use crate::components::toast::toast;
 use crate::model::{
     fallback_game_types, is_individual_game, AuthProvider, GameTypeInfo, JoinPreview,
-    OptionField, OptionKind, PlayerRating, User,
+    MyGame, OptionField, OptionKind, PlayerRating, User,
 };
 
 /// Human-readable label for a provider name ("google" -> "Google").
@@ -292,6 +292,8 @@ pub fn LobbyPage() -> View {
     let auth_providers = create_signal(Vec::<AuthProvider>::new());
     // The player's Elo ratings, one row per game type played.
     let ratings = create_signal(Vec::<PlayerRating>::new());
+    // Live games the player is seated in, for the "Continue" list.
+    let my_games = create_signal(Vec::<MyGame>::new());
     let error = create_signal(Option::<String>::None);
     let code = create_signal(String::new());
     let game_types = create_signal(fallback_game_types());
@@ -386,6 +388,9 @@ pub fn LobbyPage() -> View {
                         if let Ok(p) = api::my_ratings().await {
                             ratings.set(p.results);
                         }
+                        if let Ok(games) = api::my_games().await {
+                            my_games.set(games);
+                        }
                     });
                 }
                 user.set(Some(me));
@@ -549,6 +554,69 @@ pub fn LobbyPage() -> View {
                                     "Play scopone scientifico and briscola with friends."
                                 }
                             }
+                            // Ongoing games: a "Continue" link back into a
+                            // match whose page was accidentally closed.
+                            (move || {
+                                let games = my_games.get_clone();
+                                if games.is_empty() {
+                                    return view! {};
+                                }
+                                let types = game_types.get_clone();
+                                let rows = games
+                                    .into_iter()
+                                    .map(|g| {
+                                        let name = if g.game_name.is_empty() {
+                                            types
+                                                .iter()
+                                                .find(|t| t.id == g.game_type)
+                                                .map(|t| t.name.clone())
+                                                .unwrap_or_else(|| g.game_type.clone())
+                                        } else {
+                                            g.game_name.clone()
+                                        };
+                                        let phase = g.phase_label();
+                                        let seats = g.seats_text();
+                                        let players = g.players_text();
+                                        let players_note = if players.is_empty() {
+                                            String::new()
+                                        } else {
+                                            format!(" · {players}")
+                                        };
+                                        let href = format!("/game/{}", g.id);
+                                        view! {
+                                            li(
+                                                class="list-group-item d-flex flex-wrap \
+                                                       justify-content-between \
+                                                       align-items-center gap-2"
+                                            ) {
+                                                div {
+                                                    div(class="fw-semibold") { (name) }
+                                                    div(class="text-secondary small") {
+                                                        (phase) " · " (seats)
+                                                        (players_note)
+                                                    }
+                                                }
+                                                a(
+                                                    class="btn btn-sm btn-warning",
+                                                    href=href,
+                                                ) {
+                                                    "Continue"
+                                                }
+                                            }
+                                        }
+                                    })
+                                    .collect::<Vec<_>>();
+                                view! {
+                                    div(class="card mb-4") {
+                                        div(class="card-header") { "Your games" }
+                                        div(class="card-body p-0") {
+                                            ul(class="list-group list-group-flush") {
+                                                (rows)
+                                            }
+                                        }
+                                    }
+                                }
+                            })
                             div(class="row g-4") {
                                 div(class="col-lg-7") {
                                     div(class="card h-100") {