fix(ente): add bucket CORS policy

ente/config/bucket-cors-policy.json

@@ -0,0 +1,22 @@
+{
+  "CORSRules": [
+    {
+      "AllowedOrigins": ["https://ente.icb4dc0.de"],
+      "AllowedMethods": ["GET", "PUT", "POST"],
+      "AllowedHeaders": [
+        "Authorization",
+        "Content-Type",
+        "x-amz-date",
+        "x-amz-content-sha256",
+        "x-amz-user-agent"
+      ],
+      "ExposeHeaders": [
+        "x-amz-server-side-encryption",
+        "x-amz-request-id",
+        "x-amz-id-2",
+        "ETag"
+      ],
+      "MaxAgeSeconds": 600
+    }
+  ]
+}