Add cancellation token to the PlaywrightService.

[jbarden]

Summary

Add cancellation token to the PlaywrightService.

Update App config to support overriding the appsettings in the tests - it was working but by luck, now the order of appsetting application is deterministic

Type of change

• Feature
• Bug fix
• Refactor
• CI/CD
• Documentation
• Maintenance

Related issues / links

None

How was this tested?

• Unit tests added/updated
• Manual validation
• Not applicable

Impacted areas

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TDD Checklist (required)

• Builds locally
• Tests pass (dotnet test)
• No new analyzer warnings
• Public API changes reviewed
• Documentation updated (if applicable)
• Not applicable

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How to run tests locally

# Restore and run tests
dotnet restore AStar.Dev.slnx
dotnet test --verbosity normal

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Notes for reviewers

• Ensure CI passed for all OS runners where configured.