feat(web): show active sandbox details in Box status popover

Display sandbox count and a detailed list of active sessions including
session ID, image, backend, resources (CPU/memory), network mode, and
last used time. Fetched from GET /api/v1/box/sessions in parallel.
Includes i18n for all 8 supported languages.

web/src/i18n/locales/en-US.ts

@@ -473,7 +473,12 @@ const enUS = {
     boxUnavailable: 'Unavailable',
     boxBackend: 'Backend',
     boxProfile: 'Profile',
+    boxSandboxes: 'Sandboxes',
     boxErrors: 'Errors',
+    boxSessionImage: 'Image',
+    boxSessionBackend: 'Backend',
+    boxSessionResources: 'Resources',
+    boxSessionNetwork: 'Network',
     boxStatusLoadFailed: 'Failed to load Box status',
     failedToGetDebugInfo: 'Failed to get debug information',
     copiedToClipboard: 'Copied to clipboard',