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/ja.json

@@ -829,6 +829,9 @@
     "portfolio_remove_from": "ポートフォリオから削除",
     "portfolio_revert": "元に戻す",
     "portfolio_save": "保存",
+    "portfolio_save_need_address": "保存するにはアドレスを1つ以上追加してください。",
+    "portfolio_save_need_name": "このグループを保存するには名前を入力してください。",
+    "portfolio_save_need_price": "保存するには0より大きい手動価格を入力してください。",
     "portfolio_search": "アドレスを検索…",
     "portfolio_search_icons": "アイコンを検索…",
     "portfolio_select_all": "すべて",