Improved drawing sync: MIME detection, WebP/JPEG support, sync log + frontend updates

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

frontend/public/manifest.json

@@ -2,16 +2,39 @@
   "name": "InkNote",
   "short_name": "InkNote",
   "description": "Write & draw — notes that sync everywhere",
-  "start_url": ".",
-  "scope": ".",
+  "start_url": "./",
+  "scope": "./",
+  "id": "/",
   "display": "standalone",
   "background_color": "#0d1117",
   "theme_color": "#0d1117",
   "orientation": "any",
   "categories": ["productivity", "utilities"],
   "icons": [
-    { "src": "icon-192.png", "sizes": "192x192", "type": "image/png", "purpose": "any maskable" },
-    { "src": "icon-512.png", "sizes": "512x512", "type": "image/png", "purpose": "any maskable" }
+    {
+      "src": "./icon-192.png",
+      "sizes": "192x192",
+      "type": "image/png",
+      "purpose": "any"
+    },
+    {
+      "src": "./icon-512.png",
+      "sizes": "512x512",
+      "type": "image/png",
+      "purpose": "any"
+    },
+    {
+      "src": "./icon-192.png",
+      "sizes": "192x192",
+      "type": "image/png",
+      "purpose": "maskable"
+    },
+    {
+      "src": "./icon-512.png",
+      "sizes": "512x512",
+      "type": "image/png",
+      "purpose": "maskable"
+    }
   ],
   "prefer_related_applications": false
 }