feat(plot): paper catalogue with AutoCAD canonical media names

AutoCAD stores a layout's sheet as the plotter driver's canonical media
name (`ISO_A4_(210.00_x_297.00_MM)`, `ANSI_full_bleed_B_(11.00_x_17.00_Inches)`),
so a drawing saved here has to carry the same spelling for AutoCAD to find
the sheet in its DWG To PDF list, and a name that arrives from AutoCAD must
resolve to its dimensions and go back out untouched.

- New `io::paper_catalog` replaces the eight-entry `paper_sizes`: ISO A/B,
  ANSI, ARCH (incl. E1) and JIS series with full-bleed / expand variants,
  Letter / Legal / Tabloid, millimetre and inch units, a parser that
  reconstructs any well-formed AutoCAD name (custom or driver-specific)
  from its embedded dimensions, driver / legacy-config aliases (`A4`,
  `Letter`, `Ledger`), and dimension matching that prefers the plain sheet.
- The Plot dialog stores the canonical name and shows the sheet as
  `ISO A4 (210 × 297 mm)`; a sheet that only exists in the drawing is
  listed first so it stays selectable.
- A sheet the user did not change keeps the drawing's own media name
  (`paper_name_for_settings`), so a Windows printer's `A4` is not rewritten
  to `ISO_A4_(…)` just by passing through the dialog.
- Drops the unused `PlotFormat` / `PlotOrientation` messages,
  `paper_label_from_dims`, and three duplicated `match "A4" | …` tables.

Tests: catalogue spelling, parser round-trip, aliases, dimension matching,
display formatting, plus dialog ↔ layout round-trips for driver-named,
catalogue and unknown sheets.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

src/app/update/mod.rs

@@ -8497,14 +8497,6 @@ impl OpenCADStudio {
             Message::PlotExportPath(None) => Task::none(),
             Message::PlotExportPath(Some(path)) => self.on_plot_export_path_some(path),
 
-            Message::PlotFormat(f) => {
-                self.plot_format = f;
-                Task::none()
-            }
-            Message::PlotOrientation(o) => {
-                self.plot_orientation = o;
-                Task::none()
-            }
             Message::PlotWindowExport => {
                 let i = self.active_tab;
                 let stem = self.tabs[i]