fix(eps): a layer's state after its last blend stays the layer's

#4757 gives a blend the Xy written after its record. When the blend is a
layer's last object, the layer's own state block (Xy, Xd, 7 () XW, LB)
went to the blend instead, and the layer stayed opaque. The blend's state
is now tentative like a mesh's (#4748): its own 6 () XW confirms it, the
layer's LB gives it to the layer and the blend keeps what it had.

Also records the .ai/EPS audit fixes under G9, the File formats row and M4.

docs/file-format-parity.md

@@ -132,6 +132,7 @@ the app's own editing copy of a file (an EPS after its `%%EOF`, a `.ai`'s `AIPri
 
 | Date | Change | Summary |
 |---|---|---|
+| 2026-10-30 | minor | `.ai`/EPS editing data: a blend takes the transparency (opacity, blend mode, knockout; blends are written with knockout on) in the state block after its record, as a group takes the one after its end; it was left for the next object, so a blend's steps of falling opacity drew over each other instead of knocking each other out, and every such blend came in too dark (a user's file has 143, its bubbles came in as dark rings). Both a live blend and drawn steps kept as a group take it. Test `import::ai::tests::a_blends_transparency_follows_its_record`; checked locally against that file: it comes 1.3% → 0.6% nearer its page, though a mesh seen through a mesh-shaped opacity mask still keeps it just over the limit. When a blend is the layer's last object and the layer's own state block (`7 () XW`, then `LB`) follows, the state is the layer's and the blend keeps its own, as for meshes (#4748); scores unchanged |
 | 2026-10-31 | minor | PDF (and `.ai`) with Illustrator editing data saved with only some of its artboards: its pages are those artboards, while the editing data keeps them all, and the layers were compared with the first page on the first artboard, so a page of the second artboard came in as the PDF part, without its layers. With fewer pages than artboards, the first page is now taken to be the artboard of its size whose art draws most like it (up to 16 weighed), and the pages' type goes to that artboard and the ones after it. All artboards come in, as before. Test `import::tests_native::a_pdf_of_its_second_artboard_is_compared_on_that_artboard`; scores unchanged |
 | 2026-10-30 | minor | `.ai`/EPS editing data: a blend takes the transparency (opacity, blend mode, knockout; blends are written with knockout on) in the state block after its record, as a group takes the one after its end; it was left for the next object, so a blend's steps of falling opacity drew over each other instead of knocking each other out, and every such blend came in too dark (a user's file has 143, its bubbles came in as dark rings). Both a live blend and drawn steps kept as a group take it. Test `import::ai::tests::a_blends_transparency_follows_its_record`; checked locally against that file: it comes 1.3% → 0.6% nearer its page, though a mesh seen through a mesh-shaped opacity mask still keeps it just over the limit; scores unchanged |
 | 2026-10-30 | minor | `.ai`/EPS editing data: a gradient mesh with an opacity mask takes the transparency (`Xy`) written after the mask's dictionary, as one without a mask takes the one right after its `/End X!`; the operators of the mask's art (on `%_` lines) hid it, so the state was read as the next object's and each masked mesh in a run drew with the blend mode of the one before it (a Multiply shading drawn Normal, an Overlay tint drawn Multiply over the art below). Test `import::ai::tests::a_masked_gradient_mesh_takes_the_transparency_written_after_its_mask`; checked locally against a user's files: one opens from its layers 0.1% from its page (it was 0.6%, just inside the limit), another comes 1.6% → 1.3% nearer; scores unchanged |