feat(testing): LEDGER — migration inventory differ

[kristopherjturner]

LEDGER — Migration inventory differ

Classification (ADR-0004)

Axis	Value
Scope	platform-feature
Target	repo
Authority	contract
Lifecycle	pre-deploy · post-deploy

Summary

Before/after inventory diffs for VM conversion and Nutanix cutover. Platform owns the diff contract (what fields must be present in before/after snapshots, what delta counts as a failure); repos supply the actual inventories.

Deferral rationale

azurelocal-vm-conversion-toolkit and azurelocal-nutanix-migration need to establish their own test surfaces first. The contract cannot be designed without seeing what they actually inventory.

Acceptance criteria

• azurelocal-vm-conversion-toolkit test surface established
• azurelocal-nutanix-migration test surface established
• Diff contract schema designed (required fields in before/after snapshots, failure thresholds)
• AzureLocal.Ledger module or reusable workflow
• Module docs added under docs/

Target: v0.3.0+