fix(chat): repair Arco migration fallout in the chat page

The Phase 006 walkthrough surfaced four issues the automated checks could
not see. Dead naive-ui class names left behind by the migration stopped
matching, tooltips that carried their label as trailing default-slot text
leaked that text into the flex row, the workspace panel squeezed the chat
column until the input toolbar wrapped, and the Escape fallback still
looked for naive-ui's modal mask.

Tooltips now pass their label through the content prop, the tool panel
reserves a minimum width for the chat column, and Escape finds the visible
Arco modal and clicks its close button.

packages/client/src/composables/useKeyboard.ts

@@ -36,12 +36,14 @@ export function useKeyboard() {
         closeSessionSearch()
         return
       }
-      // Close any open modals — naive-ui handles this internally
-      const modal = document.querySelector('.n-modal-mask')
-      if (modal) {
-        const closeBtn = modal.querySelector('.n-base-close') as HTMLElement
-        closeBtn?.click()
-      }
+      // 聊天页的弹窗已全部迁到 Arco（且都带 unmount-on-close），Esc 兜底要查
+      // Arco 的类名，否则模型选择、会话搜索这些弹窗在键盘下关不掉。
+      const openModal = Array.from(
+        document.querySelectorAll<HTMLElement>('.arco-modal'),
+      ).find((el) => el.offsetParent !== null)
+      openModal
+        ?.querySelector<HTMLElement>('.arco-modal-close-btn')
+        ?.click()
     }
   }