feat: Pester test coverage for all conversion scripts

[kristopherjturner]

Overview

Implement Pester test coverage for all scripts in the toolkit. Tests should mock Hyper-V and Azure Arc cmdlets to enable execution in CI environments without real cluster access.

Scope

• Pester v5 test suites for all scripts in scripts/azurelocal/ and scripts/hyperv/
• Mock implementations of Hyper-V cmdlets (Get-VM, Set-VM, Stop-VM, etc.)
• Mock implementations of Azure Arc cmdlets (Get-AzConnectedMachine, etc.)
• Test cases: happy path, pre-flight failure, mid-conversion failure, rollback trigger
• Code coverage reporting (target: ≥80% function coverage)
• CI integration: tests run on every PR

Acceptance Criteria

• All scripts have Pester test suites in tests/
• Tests run in CI without real Hyper-V or Arc environment
• ≥80% function coverage across all scripts
• Pre-flight failure and rollback scenarios have explicit test cases
• Coverage report generated as a CI artifact

Dependencies

• Parent Epic: [Epic] VM Conversion Toolkit Full Build-Out #5
• Azure Local path scripts: feat: script refinement — Azure Local conversion path (01–05 scripts) #6
• Hyper-V path scripts: feat: script refinement — Hyper-V standalone conversion path #7