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/util.rs

@@ -62,27 +62,6 @@ pub(super) fn layout_entry_name(s: &str) -> &str {
     s.trim_start_matches('*').trim_end_matches('*')
 }
 
-/// Infer an A-series label when dimensions match; otherwise retain the size.
-pub(super) fn paper_label_from_dims(w: f64, h: f64) -> (String, String) {
-    use crate::io::paper_sizes::PaperSize;
-    let orient = if w >= h { "Landscape" } else { "Portrait" };
-    let (short, long) = if w <= h { (w, h) } else { (h, w) };
-    let mut best = ("A4".to_string(), f64::INFINITY);
-    for p in PaperSize::ALL {
-        let (pw, ph) = p.dimensions_mm(); // portrait: pw < ph
-        let err = (pw - short).abs() + (ph - long).abs();
-        if err < best.1 {
-            best = (p.label().to_string(), err);
-        }
-    }
-    let label = if best.1 <= 2.0 {
-        best.0
-    } else {
-        format!("{w:.2} × {h:.2} mm")
-    };
-    (label, orient.to_string())
-}
-
 pub(super) fn parse_plot_scale(s: &str) -> (f64, f64) {
     if s == "Fit" {
         return (1.0, 1.0);