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/command_zone_test_common.h

@@ -0,0 +1,22 @@
+/**
+ * @file command_zone_test_common.h
+ * @brief Shared types and utilities for command zone unit tests.
+ *
+ * Provides access to production CommandZoneType and ZoneVisibility enums
+ * without pulling in full Qt graphics dependencies. Tests remain isolated
+ * while using the canonical enum definitions.
+ */
+
+#ifndef COMMAND_ZONE_TEST_COMMON_H
+#define COMMAND_ZONE_TEST_COMMON_H
+
+#include "cockatrice/src/game/zones/command_zone_types.h"
+
+// Re-export the minimized height ratio using the canonical constant name
+// that tests were already using (ZoneSizes vs CommandZoneConstants)
+namespace ZoneSizes
+{
+using namespace CommandZoneConstants;
+}
+
+#endif // COMMAND_ZONE_TEST_COMMON_H