M3: copy with formatting: keep columns apart, name families by their last part

- A line change into a block of another style is a wrap only when the next
  line starts within half a line below the last one; a line far above it
  (the next column) starts a paragraph. The size compare treats NaN as
  "not the same size".
- A smaller block must overlap a block's interior, not just touch its edge,
  to stop the block being used as a hint.
- font_family drops only the part after the last hyphen, and only when it
  names a style (Segoe-UI-Bold gives Segoe UI).
- text_extract's description and html_truncated doc now cover a page's own
  copy caps and say that rect HTML is in line order.
- Parity: the new tests are evidence; column selection HTML is listed as
  missing (plain text only).

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01SqmHYx8FiWM5PcsoiErgp9

parity/acrobat-features.toml

@@ -1574,8 +1574,8 @@ milestone = "M3"
 status = "partial"
 commands = ["edit.copy"]
 tools = ["text_extract"]
-evidence = ["crates/export/src/clip.rs::heading_body_and_coloured_span_keep_their_formatting", "crates/export/src/clip.rs::special_characters_are_escaped_and_cannot_leave_the_style", "crates/export/src/clip.rs::empty_and_huge_selections_are_bounded", "crates/export/src/clip.rs::invisible_controls_and_bidi_overrides_are_dropped", "crates/export/src/clip.rs::font_sizes_stay_within_range", "crates/engine/src/rich_copy.rs::copy_keeps_headings_body_and_colour_as_html", "crates/engine/src/rich_copy.rs::copy_with_formatting_is_refused_when_copying_is_withheld", "crates/engine/src/rich_copy.rs::running_out_of_match_steps_copies_the_rest_unstyled", "crates/automation/tests/it/automation.rs::text_extract_as_html_keeps_the_formatting", "crates/automation/src/tests.rs::text_extract_html_has_one_budget_across_pages", "crates/ui-egui/tests/it/text_select.rs::selected_text_copy_keeps_the_formatting_as_html", "crates/ui-egui/tests/it/text_select.rs::selected_text_copy_falls_back_to_plain_text_when_html_is_refused", "crates/ui-egui/tests/it/text_select.rs::selected_text_copy_with_formatting_honours_permissions"]
-notes = "Copy of a page-text selection also puts HTML on the system clipboard (paragraphs, bold, italic, size, colour, font family; plain text as the alternative), and text_extract format html returns the same. Missing: RTF, underline and strike-through, tables, Select All of the whole document (plain text only), the web build (plain text only), and styles for glyphs outside the page's reading blocks (copied unstyled)"
+evidence = ["crates/export/src/clip.rs::heading_body_and_coloured_span_keep_their_formatting", "crates/export/src/clip.rs::special_characters_are_escaped_and_cannot_leave_the_style", "crates/export/src/clip.rs::empty_and_huge_selections_are_bounded", "crates/export/src/clip.rs::invisible_controls_and_bidi_overrides_are_dropped", "crates/export/src/clip.rs::font_sizes_stay_within_range", "crates/engine/src/rich_copy.rs::copy_keeps_headings_body_and_colour_as_html", "crates/engine/src/rich_copy.rs::copy_with_formatting_is_refused_when_copying_is_withheld", "crates/engine/src/rich_copy.rs::running_out_of_match_steps_copies_the_rest_unstyled", "crates/engine/src/rich_copy.rs::a_style_change_at_a_line_end_stays_in_its_paragraph", "crates/engine/src/rich_copy.rs::a_style_change_into_the_next_column_starts_a_paragraph", "crates/engine/src/rich_copy.rs::a_styled_word_inside_a_paragraph_keeps_its_style", "crates/engine/src/rich_copy.rs::a_capped_copy_is_marked_truncated", "crates/engine/src/rich_copy.rs::without_an_editor_the_styles_are_incomplete", "crates/ui-egui/tests/it/column_select.rs::a_column_selection_copies_plain_text_only", "crates/automation/tests/it/automation.rs::text_extract_as_html_keeps_the_formatting", "crates/automation/src/tests.rs::text_extract_html_has_one_budget_across_pages", "crates/ui-egui/tests/it/text_select.rs::selected_text_copy_keeps_the_formatting_as_html", "crates/ui-egui/tests/it/text_select.rs::selected_text_copy_falls_back_to_plain_text_when_html_is_refused", "crates/ui-egui/tests/it/text_select.rs::selected_text_copy_with_formatting_honours_permissions"]
+notes = "Copy of a page-text selection also puts HTML on the system clipboard (paragraphs, bold, italic, size, colour, font family; plain text as the alternative), and text_extract format html returns the same. Missing: RTF, underline and strike-through, tables, Select All of the whole document (plain text only), the web build (plain text only), styles for glyphs outside the page's reading blocks (copied unstyled), and HTML for a column selection (plain text only; text_extract with rect gives its HTML in line order, not as the column's rows)"
 
 [[feature]]
 id = "view.snapshot"