[UserList] Add invite button to hover popup (#7144)

* [Client] Send game invites from the user context menu via a private message

The user context menu gains an "Invite to Game" submenu listing the
inviteable games in the room (the inviter's own games, honoring the
buddy-only setting). Picking one opens a private message to the target
user with a cockatrice://joingame link naming the game, so the target
gets a clickable invite instead of a raw URL. Multi-game rooms offer a
picker; a single inviteable game sends directly. Sending a message to
an offline user no longer swallows the draft — it reports that the
user is offline and keeps the typed text.

Took 30 seconds

Took 1 minute

* [Client] Open the invite dialog taller by default without enforcing a minimum size

---------

Co-authored-by: Lukas Brübach <Bruebach.Lukas@bdosecurity.de>

cockatrice/src/interface/widgets/server/user/user_info_popup.cpp

@@ -525,6 +525,13 @@ void UserInfoPopup::rebuildActionButtons(const ServerInfo_User &userInfo, bool o
     connect(games, &QPushButton::clicked, this, [this, name] { emit showGamesRequested(name); });
     add(games);
 
+    // ── Invite (only while the inviter has a joinable game for this user) ────
+    if (!isSelf && online && gameInviteAvailable && gameInviteAvailable(name)) {
+        auto *invite = makeBtn(tr("Invite"), tr("Invite to your game"), actionArea, theme);
+        connect(invite, &QPushButton::clicked, this, [this, name] { emit inviteRequested(name); });
+        add(invite);
+    }
+
     // ── Buddy / ignore (registered users only) ────────────────────────────────
     if (!isSelf && isReg) {
         if (isBuddy) {