feat(core): 引入 plan/effect 执行骨架

新增 plan/effect 数据结构与基础操作
在 runtime 中接入 event -> command_buffer -> plan -> backend 流程
补齐 policy/backend 接口并同步更新测试构建

tests/config/CMakeLists.txt

@@ -41,9 +41,12 @@ add_executable(${RUNTIME_CONFIG_TEST_APP_NAME}
     ${SOURCE_DIR}/config/defaults.c
     ${SOURCE_DIR}/config/loader.c
     ${SOURCE_DIR}/config/runtime_config.c
+    ${SOURCE_DIR}/core/command_buffer.c
     ${SOURCE_DIR}/core/event.c
     ${SOURCE_DIR}/core/layer.c
     ${SOURCE_DIR}/core/layout.c
+    ${SOURCE_DIR}/core/plan.c
+    ${SOURCE_DIR}/core/policy.c
     ${SOURCE_DIR}/core/rules.c
     ${SOURCE_DIR}/core/runtime.c
     ${SOURCE_DIR}/core/state.c

tests/config/runtime_config_test.c

@@ -22,6 +22,11 @@ bool backend_next_event(backend_t *backend, event_t *event) {
   return false;
 }
 
+bool backend_apply_effect(backend_t *backend, const effect_t *effects,
+                          size_t effect_count) {
+  return false;
+}
+
 static backend_t *test_backend_create(void) {
   return calloc(1, sizeof(backend_t));
 }