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.

tests/command_zone/CMakeLists.txt

@@ -105,6 +105,21 @@ target_link_libraries(counter_visibility_test
 
 add_test(NAME counter_visibility_test COMMAND counter_visibility_test)
 
+# ------------------------
+# Server Counter SetCount Test
+# Tests setCount() return value for event suppression
+# ------------------------
+add_executable(server_counter_setcount_test
+    server_counter_setcount_test.cpp
+)
+
+target_link_libraries(server_counter_setcount_test
+    PRIVATE Threads::Threads
+    PRIVATE ${GTEST_BOTH_LIBRARIES}
+)
+
+add_test(NAME server_counter_setcount_test COMMAND server_counter_setcount_test)
+
 # ------------------------
 # Dependencies on gtest
 # ------------------------
@@ -114,4 +129,5 @@ if(NOT GTEST_FOUND)
     add_dependencies(command_zone_state_test gtest)
     add_dependencies(command_zone_integration_test gtest)
     add_dependencies(counter_visibility_test gtest)
+    add_dependencies(server_counter_setcount_test gtest)
 endif()