Make tessellation memo and resident wire set zoom-independent

With GPU analytical rendering handling circles, arcs, and ellipses,
tessellation geometry is now camera- and zoom-independent.

- Remove wpp from the tessellation memo guard hash to prevent clearing
  all cached entities when zooming across quantization bands.
- Remove quantized_wpp from resident_wire_key and resident_wires_for
  so all zoom levels reuse the cached resident set directly with zero
  CPU re-tessellation.
- Fix clippy slice_from_raw_parts lint in dwg-thumbnailer without suppression.
- Update zoom test to assert Arc pointer equality across camera zooms.

crates/dwg-thumbnailer/src/lib.rs

@@ -259,7 +259,7 @@ pub unsafe extern "C" fn dwg_thumbnail_png(
 #[no_mangle]
 pub unsafe extern "C" fn dwg_thumbnail_free(ptr: *mut u8, len: usize) {
     if !ptr.is_null() && len != 0 {
-        drop(Box::from_raw(std::slice::from_raw_parts_mut(ptr, len)));
+        drop(Box::from_raw(std::ptr::slice_from_raw_parts_mut(ptr, len)));
     }
 }