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/zh.json

@@ -829,6 +829,9 @@
     "portfolio_remove_from": "从投资组合中移除",
     "portfolio_revert": "还原",
     "portfolio_save": "保存",
+    "portfolio_save_need_address": "添加至少一个地址以保存。",
+    "portfolio_save_need_name": "输入名称以保存此分组。",
+    "portfolio_save_need_price": "输入大于 0 的手动价格以保存。",
     "portfolio_search": "搜索地址…",
     "portfolio_search_icons": "搜索图标…",
     "portfolio_select_all": "全部",