refactor(core/policy): 从 policy_context_t 中提取 event 为独立参数

policy_context_t 应该只包含所有 policy 相关接口都需要用到的参数，而
event 只是 policy_route_event 接口需要的参数，故应该将其从
policy_context_t 中剔除

src/core/policy.c

@@ -93,13 +93,17 @@ static bool route_map_request(
   return true;
 }
 
-bool policy_route_event(const policy_context_t *ctx, command_buffer_t *out) {
+bool policy_route_event(
-  switch (ctx->event->type) {
+  const policy_context_t *ctx,
+  const event_t *event,
+  command_buffer_t *out
+) {
+  switch (event->type) {
   case ZDWM_EVENT_WINDOW_MAP_REQUEST:
     return route_map_request(
       ctx->state,
       ctx->rules,
-      &ctx->event->as.window_map_request,
+      &event->as.window_map_request,
       out
     );
   default:

src/core/policy.h

@@ -9,10 +9,23 @@
 typedef struct policy_context_t {
   const state_t *state;
   const rules_t *rules;
-  const event_t *event;
 } policy_context_t;
 
-bool policy_route_event(const policy_context_t *ctx, command_buffer_t *out);
+/**
+ * @brief 事件路由：将运行时事件翻译为语义命令
+ *
+ * @param ctx   策略上下文
+ * @param event 需要翻译的事件
+ * @param out   命令输出缓冲区，路由产生的命令追加到此处
+ *
+ * @return true     产生了至少一条需要执行的命令
+ * @return false    产生了至少一条需要执行的命令
+ */
+bool policy_route_event(
+  const policy_context_t *ctx,
+  const event_t *event,
+  command_buffer_t *out
+);
 bool policy_apply_command(
   const policy_context_t *ctx,
   const command_buffer_t *command_buffer,

src/core/runtime.c

@@ -110,6 +110,11 @@ void runtime_run(runtime_t *runtime) {
   command_buffer_t *command_buffer = &runtime->command_buffer;
   plan_t *plan                     = &runtime->plan;
 
+  policy_context_t ctx = {
+    .state = &runtime->state,
+    .rules = &runtime->rules,
+  };
+
   while (runtime->running) {
     event_t event = {0};
     if (!backend_next_event(backend, &event)) break;
@@ -117,13 +122,7 @@ void runtime_run(runtime_t *runtime) {
     command_buffer_reset(command_buffer);
     plan_reset(plan);
 
-    policy_context_t ctx = {
+    policy_route_event(&ctx, &event, command_buffer);
-      .state = &runtime->state,
-      .rules = &runtime->rules,
-      .event = &event,
-    };
-
-    policy_route_event(&ctx, command_buffer);
     policy_apply_command(&ctx, command_buffer, plan);
     if (plan->count) backend_apply_effect(backend, plan->effects, plan->count);