Harden DISM staging and servicing lifecycle recovery

[cmendesvdl]

Summary

Follow-up to merged PR #17. The final audit identified servicing lifecycle defects not covered by the original passing regressions.

• Stage DISM executable wrappers in protected, per-operation Program Files directories with trusted ancestry and exclusive file creation.
• Confirm process exit after asynchronous termination; retain incomplete cancellation and recovery identity instead of reporting success.
• Keep regular and custom cancellation in the worker holding the process handle, rather than interrupting or racing it from the UI.
• Run custom completion/stall detection inside the polling loop and block new custom builds while recovery state remains unresolved.
• Share owned-WIM cleanup between GUI and headless paths, preserving mount records and temporary content on failure.
• Add lifecycle regression coverage, CI wiring, documentation, and regenerated 20-file checksums.

Validation

• Pester 6.2.0: 59 passed, zero failures, skips, or not-run cases.
• All 10 standalone DAT regression harnesses passed.
• All 20 checksum entries verified against checked-out bytes.
• Read-only validation of actual local Program Files ancestry passed; native DirectoryInfo traversal has its own regression case.
• Workspace parser sweep: 158 PowerShell files across 13 checkouts, plus four standalone XAML files, without parse failures.
• Existing OSD/hub suites passed: disk 69, log copy 146, AD groups 234, archived hub 14.

Review and rollout limits

This is not a blanket clean-static-analysis or production-certification claim. The broader default-rule analyzer sweep has substantial pre-existing warnings and plaintext SecureString conversion findings that need contextual triage; original MSEndpointMgr histories and bundled historical code were preserved rather than mass-refactored.

Live elevated WPF/DISM, real hardware, firmware, ConfigMgr, and Intune validation remains required. The protected directory creation targets Windows PowerShell 5.1/.NET Framework; PowerShell 7 runtime compatibility is not certified. Failed or unverifiable launch/cancellation state remains fail-closed and requires identity-aware recovery.

This follow-up is intentionally submitted for review, not auto-merged under the authorization for the original numbered PRs.