feat(command-zone): add graphics implementation with integration tests

Implement CommandZone - the main Qt graphics class for rendering and
interacting with command zones.

This commit brings together all previous components:
- Uses CommandZoneState for visibility management
- Uses CommandZoneLogic for card data handling
- Uses ZoneToggleButton for visibility controls
- Uses CommanderTaxCounter for tax display
- Uses z_values.h for proper visual layering

Zone modifications for command zone support:
- SelectZone: add command zone to zone selection
- StackZone: support command zone in stack operations
- TableZone: command zone positioning integration
- ViewZoneWidget: command zone viewing support

Integration tests verify:
- Counter parenting behavior
- Zone state coordination
- Full graphics stack interaction

tests/command_zone/CMakeLists.txt

@@ -69,6 +69,26 @@ target_link_libraries(command_zone_state_test
 
 add_test(NAME command_zone_state_test COMMAND command_zone_state_test)
 
+# ------------------------
+# Command Zone Integration Test
+# Tests counter parenting and zone coordination
+# ------------------------
+add_executable(command_zone_integration_test
+    command_zone_integration_test.cpp
+)
+
+target_include_directories(command_zone_integration_test
+    PRIVATE ${CMAKE_SOURCE_DIR}
+)
+
+target_link_libraries(command_zone_integration_test
+    PRIVATE Threads::Threads
+    PRIVATE ${GTEST_BOTH_LIBRARIES}
+    PRIVATE ${TEST_QT_MODULES}
+)
+
+add_test(NAME command_zone_integration_test COMMAND command_zone_integration_test)
+
 # ------------------------
 # Counter Visibility Test
 # Tests counter visibility during zone state transitions
@@ -92,5 +112,6 @@ if(NOT GTEST_FOUND)
     add_dependencies(command_zone_logic_test gtest)
     add_dependencies(commander_tax_counter_test gtest)
     add_dependencies(command_zone_state_test gtest)
+    add_dependencies(command_zone_integration_test gtest)
     add_dependencies(counter_visibility_test gtest)
 endif()