Add AD pre-population extractor for Dr Migrate

[adamswbrown]

Summary

Implements the AD pre-population spec as a single read-only PowerShell script that pulls a complete server inventory, workload signals, and topology from Active Directory into CSVs ready to be merged into a DMC cloud-migration assessment.

The nine queries from the spec, plus a derived workload classification:

• ad_servers.csv — authoritative enabled-server list (OS, last logon, OU, owner)
• ad_spns_computer.csv — SPNs against computer objects
• ad_spns_service_accounts.csv — SPNs against domain user accounts (catches SQL/Exchange/IIS running as service accounts)
• ad_spns_gmsa.csv — SPNs against Group Managed Service Accounts
• ad_workload_classification.csv — derived per-host workload hints from joined SPN data + reference table
• ad_sites.csv, ad_subnets.csv — topology
• ad_ou_distribution.csv — top-3-level OU counts
• ad_stale_servers.csv — inactive past StaleThresholdDays (default 90)
• ad_domain_controllers.csv — DCs (usually out of migration scope)
• ad_coverage_summary.csv — single-row summary for the customer conversation
• ad_run_status.csv — per-query status with row counts and any errors

Read-only; runs as any authenticated domain user. Logs to stderr so stdout stays clean. Each query is wrapped in try/catch — partial output is preferred over no output. Supports -Server, -Credential, -StaleThresholdDays, -TimestampOutput for snapshotting.

Test plan

• Verify on a Windows 5.1 host with RSAT against a small lab domain
• Verify on PowerShell 7.x (UTF8BOM encoding path)
• Confirm stale-server filter respects -StaleThresholdDays
• Confirm -TimestampOutput creates a dated subdirectory and re-runs don't clobber prior snapshots
• Spot-check ad_workload_classification.csv against a known SQL host (workload should be derived from the service-account SPN, not the computer SPN)
• Confirm gMSA query degrades gracefully on domains with no gMSAs (empty CSV, no error)

https://claude.ai/code/session_01Mv4u6bByTyy75mWPzod2Y4

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