ci: run mypy on tests and add initial typing for ssh and tui tests

[ishan372or]

Description

What is this PR

• Bug fix
• Addition of a new feature
• Other

Why is this PR needed?
Tests were previously excluded from mypy to avoid maintenance burden.
To evaluate feasibility and improve readability where helpful, this PR enables mypy checking for tests and adds an initial, minimal set of type hints. This helps surface real typing issues early and establishes patterns for future incremental improvements.

What does this PR do?
Enables mypy checking for test files.
Adds minimal, targeted type hints to selected SSH test files.

References

Related issue: #532 – Extend type hints to tests

How has this PR been tested?

Ran pre-commit run mypy --all-files locally

Is this a breaking change?

No

Does this PR require an update to the documentation?

No

Checklist:

• The code has been tested locally
• Tests have been added to cover all new functionality
• The documentation has been updated to reflect any changes
• The code has been formatted with pre-commit