feat: detail page attachments, preview, and file metadata

Add file displayName/sortOrder APIs, result preview with Excel/video support,
unified attachment/link editing, feedback modal, and AuthProvider fix.
Run prisma migrate deploy on Render builds.

Co-authored-by: Cursor <cursoragent@cursor.com>

render.yaml

@@ -3,7 +3,7 @@ services:
     name: eene-dashboard-backend
     runtime: node
     rootDir: backend
-    buildCommand: npm install --include=dev && npx prisma generate && npm run build
+    buildCommand: npm install --include=dev && npx prisma migrate deploy && npx prisma generate && npm run build
     startCommand: npm start
     envVars:
       - key: DATABASE_URL