feat(command-zone): add server-side support with tests

Implement server-side protocol and game logic for networked command
zone play.

Protocol changes:
- room_commands.proto: command zone messages and responses

Server components:
- ServerCounter: counter synchronization for commander tax
- ServerGame: command zone game state management
- ServerPlayer: player-level command zone handling
- Server/ServerProtocolHandler: command zone message routing
- Servatrice: command zone support in the main server

Design decisions:
- setCount() returns bool for event suppression (avoid duplicate events)
- Zone state synchronized across all connected clients
- Commander tax persists across zone transitions

Test coverage verifies setCount() return value behavior for proper
event suppression in networked scenarios.

servatrice/src/servatrice.cpp

@@ -965,6 +965,11 @@ bool Servatrice::permitCreateGameAsJudge() const
     return settingsCache->value("game/allow_create_as_judge", false).toBool();
 }
 
+bool Servatrice::permitCommandZone() const
+{
+    return settingsCache->value("game/allow_command_zone", true).toBool();
+}
+
 QHostAddress Servatrice::getServerTCPHost() const
 {
     QString host = settingsCache->value("server/host", "any").toString();

servatrice/src/servatrice.h

@@ -265,6 +265,7 @@ public:
     int getMaxCommandCountPerInterval() const override;
     int getMaxUserTotal() const override;
     bool permitCreateGameAsJudge() const override;
+    bool permitCommandZone() const override;
     int getMaxTcpUserLimit() const;
     int getMaxWebSocketUserLimit() const;
     int getUsersWithAddress(const QHostAddress &address) const;