Fix print completion flow for PT-P710BT and PT-P900W.

Align raster protocol bytes and print-end sequencing by printer family, add safer status polling/retry behavior, and document the changes with regression coverage to prevent protocol regressions.

Made-with: Cursor

src/lib/libptouch_protocol.h

@@ -8,5 +8,6 @@ size_t ptouch_line_payload_bytes(unsigned head_dots);
 void ptouch_fill_gf_header(uint8_t out[3], size_t line_payload_bytes);
 void ptouch_fill_esc_iz(uint8_t out[13], uint8_t media_kind, uint8_t media_width,
 			uint32_t raster_lines);
+uint8_t ptouch_esc_ik_value(unsigned head_dots);
 
 #endif /* LIBPTOUCH_PROTOCOL_H */