feat(ole): render EMF/WMF OLE presentations

OLE2FRAME entities whose compound file carries a metafile presentation
(Excel/Word previews, scanned WMF pages) drew only their border frame —
the old decoder scanned the raw blob for a contiguous BMP, which the
CFB sector layout almost never provides. acadrust now extracts the
picture bytes tagged by kind; the new scene/model/gdi player rasterizes
EMF and WMF record streams on the CPU (pens/brushes, polygons, paths,
DIB blits, clipping, transforms) with text drawn through the existing
system-font glyph cache, and image_model feeds the result into the
raster pipeline. Rasters (BMP/PNG/JPEG/GIF, CF_DIB) decode as before
via the image crate.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

src/scene/model/ole_pres.rs

@@ -0,0 +1,28 @@
+// OLE2FRAME binary data → presentation RGBA image.
+//
+// Extraction (compound-file walk, OlePres header parse, WMFC → EMF
+// reassembly) lives in acadrust — `extract_presentation` returns the picture
+// bytes tagged by kind. This module only decodes them: rasters through the
+// `image` crate, metafiles through the `gdi` player.
+
+use acadrust::entities::{extract_presentation, OlePresentation};
+
+use super::gdi;
+
+/// Decode the picture for an OLE2FRAME data blob. Returns RGBA + dimensions.
+pub fn decode(data: &[u8]) -> Option<(Vec<u8>, u32, u32)> {
+    match extract_presentation(data)? {
+        OlePresentation::Raster(bytes) => {
+            let img = image::load_from_memory(&bytes).ok()?;
+            let rgba = img.to_rgba8();
+            let (w, h) = rgba.dimensions();
+            if w == 0 || h == 0 {
+                return None;
+            }
+            Some((rgba.into_raw(), w, h))
+        }
+        OlePresentation::Dib(bytes) => gdi::dib::decode_packed(&bytes),
+        OlePresentation::Emf(bytes) => gdi::render_emf(&bytes),
+        OlePresentation::Wmf(bytes) => gdi::render_wmf(&bytes),
+    }
+}