Add Windows service capability filter integration coverage

Summary

• Created branch codex/windows-service-integration-capability-filter from feature/deploy-windows-service.
• Added integration coverage for OpenSpec task 6.5 in IntegrationWindowsServiceCapabilityFiltering.
• The test seeds a Windows Service deployment targeting a Linux Tentacle machine, injects runtime capabilities, and verifies the action is capability-filtered before execution.
• Asserts the deployment emits ActionCapabilityFilteredEvent, does not emit running/executing action events, does not call the execution strategy, and still completes the step/task successfully.
• Marked OpenSpec task 6.5 as complete locally in ignored openspec/.

Test plan

• Focused integration: DOTNET_ROLL_FORWARD=Major dotnet test tests/Squid.IntegrationTests/Squid.IntegrationTests.csproj --filter "FullyQualifiedName~IntegrationWindowsServiceCapabilityFiltering" --logger "console;verbosity=minimal"
• git diff --cached --check