feat(layouts): 实现 fair/fullscreen/maximize 内置布局

src/layouts/fullscreen.c

@@ -0,0 +1,18 @@
+#include "layouts/fullscreen.h"
+
+bool fullscreen(const zdwm_layout_ctx_t *ctx, zdwm_layout_result_t *out) {
+  auto windows = ctx->window_ids;
+  auto count   = ctx->window_count;
+  if (!windows || !count) return false;
+
+  zdwm_layout_result_reset(out);
+  for (size_t i = 0; i < count; ++i) {
+    zdwm_layout_item_t item = {
+      .window_id = windows[i],
+      .rect      = ctx->output_geometry,
+    };
+    zdwm_layout_result_push(out, item);
+  }
+
+  return true;
+}