fix: keep exact snapping, source drawing data and adaptive options layout

Resolve curve intersections through cadkernel, retain empty exact results, gather analytic candidates independently of tessellation, and bound material uploads. Preserve large MINSERT data while limiting rendering work; remove obsolete review narratives.

src/scene/pipeline/mesh_gpu.rs

@@ -568,12 +568,15 @@ struct MeshSurfaceParams {
     flags: [u32; 4],
 }
 
-/// Downscale a decoded RGBA buffer so neither dimension exceeds `limit`,
-/// preserving aspect ratio (scaled by whichever dimension overshoots more).
-/// `None` only for genuinely malformed input (`rgba`'s length doesn't match
-/// `width * height * 4`) — the caller falls back to the 1x1 material color
-/// in that case, same as it already does for a missing image entirely.
+fn valid_rgba_size(width: u32, height: u32, pixels: &[u8]) -> bool {
+    width > 0 && height > 0
+        && (width as usize).checked_mul(height as usize).and_then(|size| size.checked_mul(4)) == Some(pixels.len())
+}
+
 fn downscale_rgba_to_limit(width: u32, height: u32, rgba: &[u8], limit: u32) -> Option<(u32, u32, Vec<u8>)> {
+    if limit == 0 || !valid_rgba_size(width, height, rgba) {
+        return None;
+    }
     let buffer = image::RgbaImage::from_raw(width, height, rgba.to_vec())?;
     let scale = (limit as f64 / width.max(height) as f64).min(1.0);
     let new_width = ((width as f64 * scale).round() as u32).clamp(1, limit);
@@ -590,14 +593,9 @@ fn upload_rgba_texture(
     fallback: [u8; 4],
     srgb: bool,
 ) -> wgpu::TextureView {
-    // A material map's decoded dimensions come straight from the source file
-    // (`material_model::load_map_image`), uncapped — an oversized image would
-    // otherwise fail `wgpu` texture-size validation and leave the material
-    // unusable (audit: raster-image rendering already tiles to this same
-    // limit in `image_gpu.rs`; a mesh material sampled by UV can't use that
-    // per-quad tiling trick, so downscale instead of tiling).
     let limit = device.limits().max_texture_dimension_2d.max(1);
     let resized;
+    let image = image.filter(|image| valid_rgba_size(image.width, image.height, &image.rgba));
     let (width, height, pixels): (u32, u32, &[u8]) = match image {
         Some(image) if image.width > limit || image.height > limit => {
             match downscale_rgba_to_limit(image.width, image.height, &image.rgba, limit) {