💄 style(chat-input): use compact stats footer for skill tools popover (#15552)

* 💄 style(chat-input): use compact stats footer for skill tools popover

- Replace the two full-width footer rows (store / management) with a
  compact stats footer: pinned / auto counts on the left, an
  "Add Skills / Connector" store button (icon + label) and a settings
  icon button on the right.
- Right-align each item's type tag (MCP / Skills / builtin) so badges sit
  flush next to the row action instead of trailing the name.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

* ✅ test(aiAgent): mock deviceGateway in connectorOverlap exec test

execAgent reads `deviceGateway.isConfigured`, which under the happy-dom
test environment hits real t3-env and throws "server-side env var on the
client". Mock `@/server/services/deviceGateway` like the sibling device
tests do so the connector/plugin overlap cases run in isolation.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

---------

Co-authored-by: Claude Opus 4.8 <noreply@anthropic.com>

locales/en-US/setting.json

@@ -1018,6 +1018,7 @@
   "tools.activation.pinned": "Pinned",
   "tools.activation.pinned.desc": "Always On",
   "tools.add": "Add Skill",
+  "tools.addSkillOrConnector": "Add Skills / Connector",
   "tools.builtins.configure": "Configure",
   "tools.builtins.find-skills.description": "Helps users discover and install agent skills when they ask \"how do I do X\", \"find a skill for X\", or want to extend capabilities",
   "tools.builtins.find-skills.title": "Find Skills",

locales/zh-CN/setting.json

@@ -1019,6 +1019,7 @@
   "tools.activation.pinned": "固定启用",
   "tools.activation.pinned.desc": "始终注入",
   "tools.add": "集成技能",
+  "tools.addSkillOrConnector": "添加技能 / 连接器",
   "tools.builtins.configure": "配置",
   "tools.builtins.find-skills.description": "当用户询问“我该如何做 X”、“帮我找一个能做 X 的技能”或希望扩展能力时，帮助用户发现并安装助手技能",
   "tools.builtins.find-skills.title": "查找技能",