fix: no-op unknown removal, earlier-duplicate editor check, list focus for delete/undo

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>

Sources/SstData/ViewSupport.swift

@@ -134,7 +134,14 @@ public final class DictionaryViewModel: ObservableObject {
 
     /// Live feedback for the editor; `id` is the entry being edited (nil for a new one).
     public func warnings(for kind: DictionaryEntry.Kind, editing id: UUID?) -> [EntryWarning] {
-        EntryWarnings.check(kind, among: store.entries.filter { $0.id != id }, knowledge: knowledge)
+        let entries = store.entries
+        let others: [DictionaryEntry]
+        if let id, let index = entries.firstIndex(where: { $0.id == id }) {
+            others = Array(entries[..<index])
+        } else {
+            others = entries
+        }
+        return EntryWarnings.check(kind, among: others, knowledge: knowledge)
     }
 
     @discardableResult
@@ -149,6 +156,7 @@ public final class DictionaryViewModel: ObservableObject {
     }
 
     public func remove(id: UUID) {
+        guard store.entries.contains(where: { $0.id == id }) else { return }
         mutate { $0.remove(id: id) }
     }