fix: resolve upload EACCES and analysis start failure

- Dockerfile: create /app/uploads with correct ownership before switching
  to the non-root nextjs user, fixing EACCES: permission denied on mkdir
- analyse-form.tsx: send 'title' and 'query' fields (not 'question') to
  match the /api/analyses endpoint contract, fixing 400 rejection that
  showed "Analyse konnte nicht gestartet werden"

Co-Authored-By: Paperclip <noreply@paperclip.ing>

Dockerfile

@@ -23,6 +23,7 @@ COPY --from=builder --chown=nextjs:nodejs /app/drizzle ./drizzle
 COPY --from=builder --chown=nextjs:nodejs /app/migrate.mjs ./migrate.mjs
 COPY --from=builder --chown=nextjs:nodejs /app/entrypoint.sh ./entrypoint.sh
 RUN chmod +x ./entrypoint.sh
+RUN mkdir -p /app/uploads && chown nextjs:nodejs /app/uploads
 USER nextjs
 EXPOSE 3000
 ENV PORT=3000