[stuartd]

Clipboard inspection could block the tray/UI thread while another application rendered delayed clipboard data. Run inspection on a worker while keeping native clipboard access serialized, closing it on the opening thread, and rejecting cancelled or superseded results.

Also avoid rewriting unchanged Explorer associations and sending redundant shell notifications, dispose replaced viewer-menu items, and dispose browser-process wrappers from About links. Add native COM/reference/handle lifetime regressions, managed cleanup tests, a resource-ownership audit, and a read-only hang-inspection script.

Validation:

• 324 portable tests passed locally; the managed solution built with zero warnings or errors.
• Full Windows build/test/package workflow passed for the code changes: https://github.com/stuartd/ClipboardDiff/actions/runs/40388380708
• Windows validation includes the new native lifetime, registry, and tray disposal regressions, plus both release packages. The subsequent commit only updates the audit with those results.

The original laptop hang has not been reproduced or diagnosed from a stack. Manual desktop testing and inspection of the still-hung process remain useful; the audit distinguishes those limitations from the confirmed code defects.