- Add type=button to Cancel/Save buttons in editor to prevent form submission
- Add href=# and return false to quick-links to prevent default anchor behavior
- StopPropagation was already present in sidebar handlers (verified)
- Document view buttons already had type=button (verified)
These fixes ensure:
- Library/tag clicks don't bubble up and trigger wrong handlers
- Quick-link buttons don't cause unexpected navigation
- Editor buttons don't accidentally submit forms
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