feat(market): explain why the portfolio Save button is disabled

Hovering the disabled Save button now shows which requirement is missing
(name / at least one address / a manual price above 0), mirroring the
send-tab disabled-submit tooltip idiom (IsItemHovered(AllowWhenDisabled)).
The hint only appears for a validation gap — not the self-evident "nothing
changed" case.

Adds portfolio_save_need_{name,address,price} to the English source and all
eight translations; rebuilds the CJK subset font for the new JA/KO/ZH glyphs.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

res/lang/ko.json

@@ -829,6 +829,9 @@
     "portfolio_remove_from": "포트폴리오에서 제거",
     "portfolio_revert": "되돌리기",
     "portfolio_save": "저장",
+    "portfolio_save_need_address": "저장하려면 주소를 하나 이상 추가하세요.",
+    "portfolio_save_need_name": "이 그룹을 저장하려면 이름을 입력하세요.",
+    "portfolio_save_need_price": "저장하려면 0보다 큰 수동 가격을 입력하세요.",
     "portfolio_search": "주소 검색…",
     "portfolio_search_icons": "아이콘 검색\\xE2\\x80\\xA6",
     "portfolio_select_all": "전체",