[Quality] Enforce Type Hinting for src/models/

[TechieSamosa]

Add Python type hints (e.g., torch.Tensor, int, float) to the Zero-DCE function signatures.

[TechieSamosa]

If you have questions about this task, please ask in the GitHub Discussions board. Please comment 'I would like to work on this' to be assigned!

[geetanunakani]

Hi @TechieSamosa I would like to work on this issue under GSSOC 2026 .Could you please assign this issue to me ?

[TechieSamosa]

Assigned