feat(plot): Windows printer media and printable areas

The plot dialog asks CUPS printers for their sheets and margins; on Windows
the query was a stub, so every printer showed the paper catalogue with
unverified margins. The driver is now asked the way the plot dialog expects:

- windows_media (compiled and tested everywhere): the three parallel
  DeviceCapabilities tables (ids, sizes in tenths of a millimetre, 64-WCHAR
  names) become one PrinterMedia per distinct size — a rotated or
  borderless twin folds onto its sheet, catalogue sheets keep their name,
  unknown sizes carry the driver's — with the device's margins on every
  entry and the driver's default sheet found by id or by user size.
- print_to_printer (Windows): DeviceCapabilitiesW for the tables, the
  default DEVMODE for the default sheet, one portrait printer DC for the
  unprintable margins (physical offsets and extents, per device — a
  documented approximation). The DEVMODE fetch is shared with the print
  path (with_printer_devmode).
- A direct print now asks the driver for the plot's own sheet (by id, or
  as a user-defined size), so an A3 plot prints on A3 rather than shrunk
  into the driver's default; a driver that refuses the sheet is asked for
  the orientation alone.
- The capability cache remembers printers that could not be asked, so a
  slow failing query runs once per session, not on every dialog open.
- PRINTERS <name> reports a printer's sheets, margins and default sheet.

Tests: names (NUL trim, full slot, lossy), media folding and dropping,
default by id / user size / none, DC margins, paper id lookup.

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

src/locale_catalog.rs

@@ -3144,6 +3144,10 @@ pub(super) fn message_attribute(source: &str) -> Option<(&'static str, &'static
         "World" => Some(("common", "world")),
         "Write Block" => Some(("insert", "write-block")),
         "X (mm)" => Some(("plot", "x-mm")),
+        "{printer}: the printer reports no sheets; the paper catalogue is used." => Some(("plot", "printer-the-printer-reports-no-sheets-the-paper-catalogue-is-used")),
+        "{printer}: {count} sheet(s) reported" => Some(("plot", "printer-count-sheet-s-reported")),
+        "Default sheet: {sheet}" => Some(("plot", "default-sheet-sheet")),
+        "Default sheet: not reported" => Some(("plot", "default-sheet-not-reported")),
         "Default printer: {name}" => Some(("plot", "default-printer-name")),
         "Default printer: none reported by the system" => Some(("plot", "default-printer-none-reported-by-the-system")),
         "Printers: none listed by the system" => Some(("plot", "printers-none-listed-by-the-system")),