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.rb

@@ -27,4 +27,9 @@ module Libptouch
 
   STATUS_LENGTH = 32
   PNG_DEFAULT_THRESHOLD = 128
+
+  # libptouch_printer_family_t（C API と同じ値）
+  FAMILY_UNKNOWN = 0
+  FAMILY_P700 = 1
+  FAMILY_P900 = 2
 end