feat(webui): standardize discard and table actions

webui/src/components/UnsavedChangesGuard.tsx

@@ -26,6 +26,11 @@ type UnsavedChangesContextValue = {
   hasUnsavedChanges: boolean;
   registerUnsavedChanges: (registration: UnsavedChangesRegistration | null) => () => void;
   requestNavigation: (action: UnsavedNavigationAction) => void;
+  /**
+   * Route an explicit Discard button through the same confirmation used for
+   * dirty navigation. The action runs after either saving or discarding.
+   */
+  requestDiscard: (action: UnsavedNavigationAction) => void;
 };
 
 const UnsavedChangesContext = createContext<UnsavedChangesContextValue | null>(null);
@@ -72,6 +77,10 @@ export function UnsavedChangesProvider({ children }: {children: ReactNode;}) {
     setPendingAction(() => action);
   }, []);
 
+  const requestDiscard = useCallback((action: UnsavedNavigationAction) => {
+    requestNavigation(action);
+  }, [requestNavigation]);
+
   useEffect(() => {
     function onBeforeUnload(event: BeforeUnloadEvent) {
       const active = registrationRef.current;
@@ -150,8 +159,9 @@ export function UnsavedChangesProvider({ children }: {children: ReactNode;}) {
   const value = useMemo<UnsavedChangesContextValue>(() => ({
     hasUnsavedChanges,
     registerUnsavedChanges,
-    requestNavigation
-  }), [hasUnsavedChanges, registerUnsavedChanges, requestNavigation]);
+    requestNavigation,
+    requestDiscard
+  }), [hasUnsavedChanges, registerUnsavedChanges, requestDiscard, requestNavigation]);
 
   return (
     <UnsavedChangesContext.Provider value={value}>
@@ -185,7 +195,8 @@ export function UnsavedChangesProvider({ children }: {children: ReactNode;}) {
 const fallbackUnsavedChangesContext: UnsavedChangesContextValue = {
   hasUnsavedChanges: false,
   registerUnsavedChanges: () => () => undefined,
-  requestNavigation: (action) => action()
+  requestNavigation: (action) => action(),
+  requestDiscard: (action) => action()
 };
 
 export function useUnsavedChanges() {