v1.2.7 — framework upgrade

Dependency updates:

• fastapi 0.115.14 → 0.139.0 (brings starlette 1.3, pydantic 2.13) (#5)
• uvicorn 0.34.3 → 0.51.0 (#4)

No functional changes. Test suite, app startup, page rendering and HDF upload verified against the new versions.