M10: a fill whose second rectangle cuts a hole is no page background (#2992)

Review follow-ups on #2994: under even-odd any second rectangle, under nonzero
one wound the other way, can leave a hole the Word page colour would cover.
The parity note says the page colour hasn't been opened in Word yet.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Gv2WwdgjmBz33GWkwgNn3Q

parity/acrobat-features.toml

@@ -6977,7 +6977,7 @@ status = "partial"
 commands = ["export.docx"]
 tools = ["doc_export_office"]
 evidence = ["crates/export/src/lib.rs::word_does_not_invent_borders_for_aligned_invoice_fields", "crates/export/src/lib.rs::word_overlap_does_not_consume_invoice_body_space", "crates/export/src/lib.rs::word_keeps_a_page_with_a_clear_image_and_big_title_in_flow", "crates/export/src/lib.rs::word_rotated_pages_keep_separate_page_sizes_and_unique_shapes", "crates/engine/src/tests.rs::office_export_positions_follow_the_displayed_crop_rotation_and_units", "crates/automation/tests/automation.rs::exporting_an_invoice_to_word_keeps_the_watermark_out_of_flow", "crates/export/src/lib.rs::docx_is_a_word_package", "crates/export/src/lib.rs::text_colour_survives_every_format", "crates/engine/src/tests.rs::exporting_office_files_keeps_text_colour", "crates/export/src/lib.rs::grid_text_becomes_a_real_table_in_every_format", "crates/export/src/lib.rs::a_link_inside_a_sentence_is_not_a_table_column", "crates/export/src/lib.rs::sentences_that_run_on_into_links_are_not_a_table", "crates/export/src/lib.rs::a_superscript_beside_a_number_keeps_its_table", "crates/export/src/lib.rs::word_opens_text_with_control_characters_and_long_pages", "crates/engine/src/tests.rs::exporting_office_files_keeps_images", "crates/automation/tests/automation.rs::exporting_to_word_html_and_rtf", "crates/ui-egui/tests/compare.rs::export_to_word_html_and_rtf", "crates/export/src/lib.rs::docx_keeps_a_shared_page_background", "crates/edit/src/tests.rs::a_page_painted_first_with_a_full_page_fill_has_that_background", "crates/engine/src/tests.rs::exporting_to_word_keeps_the_page_background"]
-notes = "Flowing Word document: paragraphs, Heading 1/2 from larger text, bold/italic, text colour (fill as sRGB; gray/CMYK converted naively, colour spaces via cs/sc read as black), borderless detected tables with spans/empty cells (a row whose blocks run on into each other, such as a link or superscript inside a sentence, or overlap, as a paragraph's lines do, is text and not a table row, #2806), per-page sections/sizes, the page colour (a full-page opaque fill painted first, such as Edit a PDF ▸ Background) as the document background when every page shares one non-white colour (Word has no per-page background, so differing colours are dropped; #2992), and positioned editable text/artwork only for pages with rotated text or text overlapped by an image or watermark-sized text, other pages flowing with inline images (#773); synthetic invoice regression; the emitted package validates with Open XML SDK 2.20 (Office 2010 schema). Word/LibreOffice rendering of the positioned output remains unverified. Pictures on positioned pages are DrawingML anchors behind the text (a VML rectangle with an image showed no picture, #1936; not yet opened in Word); a Word file embeds at most 1000 pictures and 512 MiB of them. The earlier flowing output was checked with macOS textutil and opened in Microsoft Word (Windows). Characters XML forbids are dropped; the page size stays within Word's 22 in. Not yet: exact font matching, vector rules, arbitrary paint-order/transparency, colour per run within a paragraph, general exact layout fidelity."
+notes = "Flowing Word document: paragraphs, Heading 1/2 from larger text, bold/italic, text colour (fill as sRGB; gray/CMYK converted naively, colour spaces via cs/sc read as black), borderless detected tables with spans/empty cells (a row whose blocks run on into each other, such as a link or superscript inside a sentence, or overlap, as a paragraph's lines do, is text and not a table row, #2806), per-page sections/sizes, the page colour (a full-page opaque fill painted first, such as Edit a PDF ▸ Background) as the document background when every page shares one non-white colour (Word has no per-page background, so differing colours are dropped; #2992; checked in the XML only, not yet opened in Word), and positioned editable text/artwork only for pages with rotated text or text overlapped by an image or watermark-sized text, other pages flowing with inline images (#773); synthetic invoice regression; the emitted package validates with Open XML SDK 2.20 (Office 2010 schema). Word/LibreOffice rendering of the positioned output remains unverified. Pictures on positioned pages are DrawingML anchors behind the text (a VML rectangle with an image showed no picture, #1936; not yet opened in Word); a Word file embeds at most 1000 pictures and 512 MiB of them. The earlier flowing output was checked with macOS textutil and opened in Microsoft Word (Windows). Characters XML forbids are dropped; the page size stays within Word's 22 in. Not yet: exact font matching, vector rules, arbitrary paint-order/transparency, colour per run within a paragraph, general exact layout fidelity."
 
 [[feature]]
 id = "create.export-rtf"