fix: clarify upload errors and raise upload limits

src/dev/mindspacePreviewData.ts

@@ -25,7 +25,7 @@ export const PREVIEW_SPACE: MindSpace = {
     usedBytes: 1.2 * 1024 * 1024,
     reservedBytes: 0,
     availableBytes: 3.8 * 1024 * 1024,
-    maxFileBytes: 5 * 1024 * 1024,
+    maxFileBytes: 30 * 1024 * 1024,
     publicPageLimit: 3,
     publicPageUsed: 1,
     aiDailyLimit: 20,