Update fastapi requirement from <0.116,>=0.115 to >=0.115,<0.142 in /backend - #5

Node.js 20 is deprecated. The following actions target Node.js 20 but are being forced to run on Node.js 24: actions/checkout@v4, actions/setup-node@v4, actions/upload-artifact@v4. For more information see: https://github.blog/changelog/2025-09-19-deprecation-of-node-20-on-github-actions-runners/

src/components/Panel.tsx:59:5: Calling setState synchronously within an effect can trigger cascading renders

src/components/Panel.tsx:38:17: Fast refresh only works when a file only exports components. Use a new file to share constants or functions between components.

src/components/Panel.tsx:34:17: Fast refresh only works when a file only exports components. Use a new file to share constants or functions between components.

src/state/usePanelFolder.ts:35:5: Calling setState synchronously within an effect can trigger cascading renders