feat(dashboard): add Plugins page with enable/disable, auth status, install/remove

- New PluginsPage.tsx: full plugin management UI (list, enable/disable,
  install from git, remove, git pull updates, provider picker)
- Backend: dashboard_set_agent_plugin_enabled now also toggles the
  plugin's toolset in platform_toolsets so enabling actually makes
  tools visible in agent sessions
- Backend: /api/dashboard/plugins/hub returns auth_required + auth_command
  per plugin (checks tool registry check_fn)
- Frontend: auth_required shown as Badge + CommandBlock with copy-able
  auth command
- Fix: Select overflow in providers card (min-w-0 grid cells, removed
  truncate/overflow-hidden that clipped dropdown)
- Refactor: _install_plugin_core extracted for non-interactive reuse,
  PluginOperationError for structured error handling
- i18n: en/zh/types updated with all new plugin page strings

web/src/i18n/en.ts

@@ -76,6 +76,7 @@ export const en: Translations = {
       logs: "Logs",
       models: "Models",
       profiles: "profiles : multi agents",
+      plugins: "Plugins",
       sessions: "Sessions",
       skills: "Skills",
     },
@@ -84,6 +85,7 @@ export const en: Translations = {
     navigation: "Navigation",
     openDocumentation: "Open documentation in a new tab",
     openNavigation: "Open navigation",
+    pluginNavSection: "Plugins",
     sessionsActiveCount: "{count} active",
     statusOverview: "Status overview",
     system: "System",
@@ -256,6 +258,45 @@ export const en: Translations = {
     renamed: "Renamed",
   },
 
+  pluginsPage: {
+    contextEngineLabel: "Context engine",
+    dashboardSlots: "Dashboard slots",
+    disableRuntime: "Disable",
+    enableAfterInstall: "Enable after install",
+    enableRuntime: "Enable",
+    forceReinstall: "Force reinstall (delete existing folder first)",
+    headline:
+      "Discover, install, enable, and update Hermes plugins (`hermes plugins` parity).",
+    identifierLabel: "Git URL or owner/repo",
+    inactive: "inactive",
+    installBtn: "Install from Git",
+    installHeading: "Install from GitHub / Git URL",
+    installHint: "Use owner/repo shorthand or a full https:// or git@ clone URL.",
+    memoryProviderLabel: "Memory provider",
+    missingEnvWarn: "Set these in Keys before the plugin can run:",
+    noDashboardTab: "No dashboard tab",
+    openTab: "Open",
+    orphanHeading: "Dashboard-only extensions (no agent plugin.yaml match)",
+    pluginListHeading: "Installed plugins",
+    providerDefaults: "built-in / default",
+    providersHeading: "Runtime provider plugins",
+    providersHint:
+      "Writes memory.provider (empty = built-in) and context.engine to config.yaml. Takes effect next session.",
+    refreshDashboard: "Rescan dashboard extensions",
+    removeConfirm: "Remove this plugin from ~/.hermes/plugins/?",
+    removeHint: "Only user-installed plugins under ~/.hermes/plugins can be removed.",
+    rescanHeading: "SPA plugin registry",
+    rescanHint: "Rescan after adding files on disk so the dashboard sidebar picks up new manifests.",
+    runtimeHeading: "Gateway runtime (YAML plugins)",
+    saveProviders: "Save provider settings",
+    savedProviders: "Provider settings saved.",
+    sourceBadge: "Source",
+    authRequired: "Auth required",
+    authRequiredHint: "Run this command to authenticate:",
+    updateGit: "Git pull",
+    versionBadge: "Version",
+  },
+
   skills: {
     title: "Skills",
     searchPlaceholder: "Search skills and toolsets...",

web/src/i18n/types.ts

@@ -76,6 +76,7 @@ export interface Translations {
       logs: string;
       models: string;
       profiles: string;
+      plugins: string;
       sessions: string;
       skills: string;
     };
@@ -84,6 +85,7 @@ export interface Translations {
     navigation: string;
     openDocumentation: string;
     openNavigation: string;
+    pluginNavSection: string;
     sessionsActiveCount: string;
     statusOverview: string;
     system: string;
@@ -228,6 +230,44 @@ export interface Translations {
     };
   };
 
+  // ── Plugins page ──
+  pluginsPage: {
+    contextEngineLabel: string;
+    dashboardSlots: string;
+    disableRuntime: string;
+    enableAfterInstall: string;
+    enableRuntime: string;
+    forceReinstall: string;
+    headline: string;
+    identifierLabel: string;
+    inactive: string;
+    installBtn: string;
+    installHeading: string;
+    installHint: string;
+    memoryProviderLabel: string;
+    missingEnvWarn: string;
+    noDashboardTab: string;
+    openTab: string;
+    orphanHeading: string;
+    pluginListHeading: string;
+    providerDefaults: string;
+    providersHeading: string;
+    providersHint: string;
+    refreshDashboard: string;
+    removeConfirm: string;
+    removeHint: string;
+    rescanHeading: string;
+    rescanHint: string;
+    runtimeHeading: string;
+    saveProviders: string;
+    savedProviders: string;
+    sourceBadge: string;
+    authRequired: string;
+    authRequiredHint: string;
+    updateGit: string;
+    versionBadge: string;
+  };
+
   // ── Profiles page ──
   profiles: {
     newProfile: string;

web/src/i18n/zh.ts

@@ -75,6 +75,7 @@ export const zh: Translations = {
       logs: "日志",
       models: "模型",
       profiles: "多Agent配置",
+      plugins: "插件管理",
       sessions: "会话",
       skills: "技能",
     },
@@ -83,6 +84,7 @@ export const zh: Translations = {
     navigation: "导航",
     openDocumentation: "在新标签页中打开文档",
     openNavigation: "打开导航",
+    pluginNavSection: "插件",
     sessionsActiveCount: "{count} 个活跃",
     statusOverview: "状态概览",
     system: "系统",
@@ -253,6 +255,44 @@ export const zh: Translations = {
     renamed: "已重命名",
   },
 
+  pluginsPage: {
+    contextEngineLabel: "上下文引擎",
+    dashboardSlots: "面板插槽",
+    disableRuntime: "禁用",
+    enableAfterInstall: "安装后启用",
+    enableRuntime: "启用",
+    forceReinstall: "强制重装（先删除已有目录）",
+    headline: "发现、安装、启用和更新 Hermes 插件（对齐 `hermes plugins` CLI）。",
+    identifierLabel: "Git 地址或 owner/repo",
+    inactive: "未启用",
+    installBtn: "从 Git 安装",
+    installHeading: "从 GitHub / Git 地址安装",
+    installHint: "使用 owner/repo 简写或完整的 https:// / git@ 克隆地址。",
+    memoryProviderLabel: "记忆提供方",
+    missingEnvWarn: "在「密钥」页面设置以下变量后再运行插件：",
+    noDashboardTab: "无仪表盘标签",
+    openTab: "打开",
+    orphanHeading: "仅仪表盘扩展（无匹配的 agent plugin.yaml）",
+    pluginListHeading: "已安装插件",
+    providerDefaults: "内置 / 默认",
+    providersHeading: "运行时提供方插件",
+    providersHint:
+      "写入 config.yaml：memory.provider（留空为内置）、context.engine。下次会话生效。",
+    refreshDashboard: "重新扫描仪表盘扩展",
+    removeConfirm: "从 ~/.hermes/plugins/ 删除此插件？",
+    removeHint: "仅可移除用户安装在 ~/.hermes/plugins 下的插件。",
+    rescanHeading: "SPA 插件注册表",
+    rescanHint: "在磁盘新增文件后扫描，使侧边栏载入新 manifest。",
+    runtimeHeading: "网关运行时（YAML 插件）",
+    saveProviders: "保存提供方设置",
+    savedProviders: "提供方设置已保存。",
+    sourceBadge: "来源",
+    authRequired: "需要认证",
+    authRequiredHint: "运行此命令以完成认证：",
+    updateGit: "git pull",
+    versionBadge: "版本",
+  },
+
   skills: {
     title: "技能",
     searchPlaceholder: "搜索技能和工具集...",