feat(settings): add OpenCode support to environment check and one-click install

- Add OpenCode version detection with Go path scanning
- Add GitHub Releases API for fetching latest OpenCode version
- Add OpenCode install command to one-click install section
- Update i18n hints to include OpenCode across all locales
- Fix SettingsPage indentation formatting

src/i18n/locales/en.json

@@ -352,7 +352,7 @@
     "viewReleaseNotes": "View release notes for this version",
     "viewCurrentReleaseNotes": "View current version release notes",
     "oneClickInstall": "One-click Install",
-    "oneClickInstallHint": "Install Claude Code / Codex / Gemini CLI",
+    "oneClickInstallHint": "Install Claude Code / Codex / Gemini CLI / OpenCode",
     "localEnvCheck": "Local environment check",
     "installCommandsCopied": "Install commands copied",
     "installCommandsCopyFailed": "Copy failed, please copy manually.",

src/i18n/locales/ja.json

@@ -352,7 +352,7 @@
     "viewReleaseNotes": "このバージョンのリリースノートを見る",
     "viewCurrentReleaseNotes": "現在のバージョンのリリースノートを見る",
     "oneClickInstall": "ワンクリックインストール",
-    "oneClickInstallHint": "Claude Code / Codex / Gemini CLI をインストール",
+    "oneClickInstallHint": "Claude Code / Codex / Gemini CLI / OpenCode をインストール",
     "localEnvCheck": "ローカル環境チェック",
     "installCommandsCopied": "インストールコマンドをコピーしました",
     "installCommandsCopyFailed": "コピーに失敗しました。手動でコピーしてください。",

src/i18n/locales/zh.json

@@ -352,7 +352,7 @@
     "viewReleaseNotes": "查看该版本更新日志",
     "viewCurrentReleaseNotes": "查看当前版本更新日志",
     "oneClickInstall": "一键安装",
-    "oneClickInstallHint": "安装 Claude Code / Codex / Gemini CLI",
+    "oneClickInstallHint": "安装 Claude Code / Codex / Gemini CLI / OpenCode",
     "localEnvCheck": "本地环境检查",
     "installCommandsCopied": "安装命令已复制",
     "installCommandsCopyFailed": "复制失败，请手动复制。",