feat(edit): Header & Footer can be drawn in Times or Courier (#3754)

Headers and footers were Helvetica only. HeaderFooter takes the same
standard-face Family as Add text: the content selects /PCHelv, /PCTimes
or /PCCour, the page gains that font, and centred and right-aligned text
is placed by the chosen face's standard-14 widths. doc_header_footer
takes font, and the dialog's fixed "Font: Helvetica" label becomes a
Helvetica / Times / Courier menu.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

parity/acrobat-features.toml

@@ -2389,7 +2389,7 @@ status = "shipped"
 commands = ["edit.header_footer"]
 tools = ["doc_header_footer"]
 evidence = ["crates/ui-egui/tests/ui_group/marks.rs::header_and_footer_dialog_inserts_tokens_and_applies_to_a_subset", "crates/edit/src/tests.rs::header_and_footer_are_drawn_in_display_space_and_wrap_the_original_content", "crates/engine/src/tests.rs::headers_footers_watermarks_and_backgrounds_show_update_and_remove"]
-notes = "Helvetica only (no font choice yet); drawn in display space on rotated pages; artifact-tagged"
+notes = "Standard faces only: Helvetica, Times or Courier (#3754; no bold, italic or embedded fonts yet); drawn in display space on rotated pages; artifact-tagged"
 
 [[feature]]
 id = "edit.header-footer-update-remove"