[light] Undef LIGHT_CONTROL_FIELDS macro and assert <=16 fields

esphome/components/light/automation.h

@@ -77,6 +77,7 @@ template<uint16_t Fields, typename... Ts> class LightControlAction : public Acti
 #undef LIGHT_FIELD_APPLY_
 #undef LIGHT_FIELD_SETTER_
 };
+#undef LIGHT_CONTROL_FIELDS
 
 template<typename... Ts> class DimRelativeAction : public Action<Ts...> {
  public:

esphome/components/light/automation.py

@@ -197,6 +197,8 @@ async def light_control_to_code(config, action_id, template_arg, args):
         (CONF_WARM_WHITE, "set_warm_white", cg.float_),
         (CONF_EFFECT, None, cg.uint32),
     )
+    # Bitmask is passed as uint16_t in C++ — must stay within 16 bits.
+    assert len(FIELDS) <= 16, "LightControlAction Fields bitmask exceeds uint16_t"
 
     field_mask = sum(1 << i for i, (k, _, _) in enumerate(FIELDS) if k in config)
     control_template_arg = cg.TemplateArguments(