docs: documentation expansion for all conversion paths and scenarios

[kristopherjturner]

Overview

Expand documentation to cover all supported conversion scenarios, prerequisites, runbook walkthroughs, and troubleshooting for both the Azure Local and Hyper-V conversion paths.

Scope

• docs/getting-started.md — Prerequisites, supported OS matrix, and quickstart
• docs/runbook-azurelocal.md — Step-by-step Azure Local conversion runbook (already exists, expand)
• docs/runbook-hyperv.md — Step-by-step Hyper-V conversion runbook (already exists, expand)
• docs/gen1-vs-gen2.md — Decision guide for when to convert (already exists, expand)
• docs/troubleshooting.md — Expand with all error codes from the error catalog (feat: error handling and staged rollback capability #9)
• docs/prerequisites.md — Expand with network, Arc, and Hyper-V version requirements

Acceptance Criteria

• Getting started guide enables a new user to attempt their first conversion in under 30 minutes
• Supported OS matrix explicitly documents what is and is not supported
• Both runbooks include command examples with expected output
• Troubleshooting covers all error codes from error catalog (feat: error handling and staged rollback capability #9)
• Docs site builds without warnings

Dependencies

• Parent Epic: [Epic] VM Conversion Toolkit Full Build-Out #5
• Error handling (for error catalog): feat: error handling and staged rollback capability #9

Priority Note

Priority/medium — documentation deferred until scripts stabilize.