libptouch: P700/P900 families, optional JSON config, ESC i z and print sequencing

- Add printer_family and profile flags; load overrides from printer_families.json
- Set ESC i z page byte from profile; pass prof into ptouch_fill_esc_iz
- End print with 0x1A only (drop FF prefix); extend Ruby FFI and CLI media info
- Add reference/ptp_raster_ref.adoc; install config under share/ptouch_label

Made-with: Cursor

ruby/lib/libptouch/context.rb

@@ -151,6 +151,7 @@ module Libptouch
     def current_media_info
       info = Binding::MediaInfo.new
       raise_on_error(Binding.libptouch_get_current_media_info(@native, info.pointer))
+      fam = info[:printer_family]
       {
         media_width_code: info[:media_width_code],
         media_kind_code: info[:media_kind_code],
@@ -161,7 +162,9 @@ module Libptouch
         left_margin_dots: info[:left_margin_dots],
         right_margin_dots: info[:right_margin_dots],
         min_feed_dots: info[:min_feed_dots],
-        min_feed_mm: info[:min_feed_mm]
+        min_feed_mm: info[:min_feed_mm],
+        printer_family: fam,
+        printer_family_label: Binding.libptouch_printer_family_label(fam)
       }
     end
   end