refactor(core): reorganize module structure

core/src/document/model/raster.rs

@@ -0,0 +1,12 @@
+// SPDX-License-Identifier: GPL-3.0-or-later
+// src/document/model/raster.rs
+//
+// Raster image document model (JPEG, PNG, etc.).
+
+use std::path::PathBuf;
+
+#[derive(Clone, Debug)]
+pub struct RasterModel {
+    pub path: PathBuf,
+    pub dimensions: (u32, u32),
+}