Refactor to remove explicit any usages

[Uarmagan]

Summary

• Replace broad any usages with narrower event and store types across backend, core, and web code.
• Factor the command-palette module unwrap into a shared helper so the same Bun-specific logic is used in one place.
• Tighten tests to use real DOM and DnD event shapes where practical.

Testing

• Unit tests updated to cover the typed helpers and event flows.
• Not run (not requested).