Refresh the homepage and improve export and draft guidance

tests/protocol.test.ts

@@ -46,6 +46,29 @@ test("dataset requires five unique in-bounds viewpoints and safe paths", () => {
     assets: [{ path: "terrain.json.gz", sha256: "a".repeat(64), bytes: 100 }],
   };
   assert.equal(datasetSchema.safeParse(base).success, true);
+  assert.equal(datasetSchema.safeParse({ ...base, assets: [] }).success, false);
+  assert.equal(
+    datasetSchema.safeParse({ ...base, source: "fabric" }).success,
+    false,
+  );
+  const capture = {
+    ...base,
+    source: "fabric",
+    assets: [
+      "map.png",
+      ...base.viewpoints.flatMap((point) =>
+        ["px", "nx", "py", "ny", "pz", "nz"].map(
+          (face) => `${point.id}/${face}.png`,
+        ),
+      ),
+    ].map((path) => ({ path, sha256: "a".repeat(64), bytes: 100 })),
+  };
+  assert.equal(datasetSchema.safeParse(capture).success, true);
+  assert.equal(
+    datasetSchema.safeParse({ ...capture, assets: capture.assets.slice(1) })
+      .success,
+    false,
+  );
   assert.equal(
     datasetSchema.safeParse({ ...base, viewpoints: base.viewpoints.slice(1) })
       .success,