리노컷 자산 파이프라인 공통화와 캐스트 외형 설계

- P1 전용 스크립트를 docs/avatar-art/linocut-pipeline 으로 옮겨 persona.json 설정으로 일반화(P1 재실행 리그 바이트 동일)
- 7명 외형·상징 설계(linocut-cast.md)와 P2~P7 정면 원화 생성 프롬프트, 얼굴 없는 화풍 참조
- P1 원화 생성 프롬프트 보존

docs/avatar-art/linocut-cast-prompts/P4-front.txt

@@ -0,0 +1,5 @@
+A Korean high-school girl of seventeen, a diligent top student and class president, tense and perfectionistic. A neat, carefully groomed look; slightly too-alert eyes with faint shadows of sleeplessness under them and a tense mouth. Long straight black hair tied in a low ponytail at the nape of her neck, a few short baby hairs escaping at her temples, no bangs so her forehead and eyebrows are fully visible. She wears a navy crewneck sweater over a white collared shirt with the collar arranged neatly, and a pencil tucked behind her right ear. Very upright posture with stiff, slightly raised shoulders.
+
+She must look like one specific real person, not a generic attractive person. Natural, realistic Korean facial features: eyes of natural human size (not enlarged), a slightly uneven face, a real nose and lips, natural skin texture. Eyes, eyebrows and mouth are fully visible: no hair, hands or objects over them, and no glasses. Dignified and deeply human. Strictly NOT anime, NOT manga, NOT webtoon, NOT K-pop idol styling, no big shiny eyes, no eyelash emphasis, no glamour. No marks or wounds on the skin.
+
+Draw a completely different person from the one in the reference image. Keep exactly the same linocut relief-print style as the reference: bold carved black-indigo lines with visible gouge marks, flat areas of only two additional ink colors (muted slate blue and warm ochre) printed on cream paper with slight ink texture and imperfect registration. Keep exactly the same framing, scale and position as the reference: head, neck and shoulders only, the head the same size and at the same height in the frame, facing the viewer straight on (frontal, symmetrical), neutral closed mouth, eyes open looking straight at the viewer, shoulders level, hands out of frame. Plain flat cream background with nothing else: no flowers, no clouds, no motifs, no text.