shopfloor dashboard: use Archivo display font for TV legibility

Bundle @fontsource-variable/archivo (air-gap safe) and apply it to the shopfloor
dashboard only - a sturdy grotesque built for signage/displays, more legible
from across the shop than Inter. Rest of the app stays on Inter.

frontend/src/main.js

@@ -5,6 +5,9 @@ import App from './App.vue'
 
 // Locally-bundled Inter (air-gap safe, no Google Fonts fetch)
 import '@fontsource-variable/inter'
+// Archivo: display/signage font used on the shopfloor dashboard for
+// distance readability on TVs (air-gap safe, bundled).
+import '@fontsource-variable/archivo'
 
 // Initialize theme on app load
 import './stores/theme'