Draft: Resolve "Install Cassiopee as a PWA"

Closes #445 (closed)

src/cassiopee.webmanifest

+{
+    "name": "Cassiopée",
+    "short_name": "cassiopee",
+    "description": "Hydraulic calculators",
+    "icons": [
+        {
+            "src": "assets/icons/favicon-16x16.png",
+            "sizes": "16x16",
+            "type": "image/png"
+        },
+        {
+            "src": "assets/icons/favicon-32x32.png",
+            "sizes": "32x32",
+            "type": "image/png"
+        },
+        {
+            "src": "assets/icons/android-chrome-192x192.png",
+            "sizes": "192x192",
+            "type": "image/png"
+        },
+        {
+            "src": "assets/icons/android-chrome-512x512.png",
+            "sizes": "512x512",
+            "type": "image/png"
+        }
+    ],
+    "start_url": "index.html",
+    "display": "fullscreen",
+    "theme_color": "#003A80",
+    "background_color": "#003A80"
+}