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/binding.rb

@@ -39,7 +39,8 @@ module Libptouch
              :left_margin_dots, :uint16,
              :right_margin_dots, :uint16,
              :min_feed_dots, :uint16,
-             :min_feed_mm, :double
+             :min_feed_mm, :double,
+             :printer_family, :uint32
     end
 
     class PngOptions < FFI::Struct
@@ -51,6 +52,7 @@ module Libptouch
     end
 
     attach_function :libptouch_create, [], :pointer
+    attach_function :libptouch_printer_family_label, [:uint32], :string
     attach_function :libptouch_destroy, [:pointer], :void
     attach_function :libptouch_strerror, [:pointer], :string
     attach_function :libptouch_last_error, [:pointer], :int