fix(i18n): rename Skills title to be app-agnostic

- Remove "Claude" prefix from Skills management title
- Update descriptions to include Gemini alongside Claude Code/Codex
- Applied to all three locales: zh, en, ja

src/i18n/locales/en.json

@@ -793,8 +793,8 @@
   },
   "skills": {
     "manage": "Skills",
-    "title": "Claude Skills Management",
-    "description": "Discover and install Claude skills from popular repositories to extend Claude Code/Codex capabilities",
+    "title": "Skills Management",
+    "description": "Discover and install skills from popular repositories to extend Claude Code/Codex/Gemini capabilities",
     "refresh": "Refresh",
     "refreshing": "Refreshing...",
     "repoManager": "Repository Management",

src/i18n/locales/ja.json

@@ -793,8 +793,8 @@
   },
   "skills": {
     "manage": "Skills",
-    "title": "Claude スキル管理",
-    "description": "人気リポジトリから Claude Skills を探してインストールし、Claude Code/Codex を拡張",
+    "title": "Skills 管理",
+    "description": "人気リポジトリからスキルを探してインストールし、Claude Code/Codex/Gemini を拡張",
     "refresh": "更新",
     "refreshing": "更新中...",
     "repoManager": "リポジトリ管理",

src/i18n/locales/zh.json

@@ -793,8 +793,8 @@
   },
   "skills": {
     "manage": "Skills",
-    "title": "Claude Skills 管理",
-    "description": "从流行的仓库发现并安装 Claude 技能，扩展 Claude Code/Codex 的能力",
+    "title": "Skills 管理",
+    "description": "从流行的仓库发现并安装技能，扩展 Claude Code/Codex/Gemini 的能力",
     "refresh": "刷新",
     "refreshing": "刷新中...",
     "repoManager": "仓库管理",