fix: shorten PWA description in manifest

refs #445

src/manifest.webmanifest

 {
-  "name": "Cassiopee, tools for designing fish crossing devices for upstream and downstream migrations and hydraulic calculation for environmental and agricultural engineering",
+  "name": "Cassiopée",
   "short_name": "Cassiopee",
   "theme_color": "#1976d2",
   "background_color": "#fafafa",