Processes tags for validation by filtering exact database matches.
Returns exact matches and items that need validation separately.
Items needing validation include their pre-computed similar items,
sorted so items WITHOUT similar matches come first (better UX: "add new" before "choose existing").
Processes tags for validation by filtering exact database matches.
Returns exact matches and items that need validation separately. Items needing validation include their pre-computed similar items, sorted so items WITHOUT similar matches come first (better UX: "add new" before "choose existing").