Feature/v2/redact (#5249)

# Description of Changes

- Add manual redaction and added it to the right rail in the viewer

---

## Checklist

### General

- [ ] I have read the [Contribution
Guidelines](https://github.com/Stirling-Tools/Stirling-PDF/blob/main/CONTRIBUTING.md)
- [ ] I have read the [Stirling-PDF Developer
Guide](https://github.com/Stirling-Tools/Stirling-PDF/blob/main/devGuide/DeveloperGuide.md)
(if applicable)
- [ ] I have read the [How to add new languages to
Stirling-PDF](https://github.com/Stirling-Tools/Stirling-PDF/blob/main/devGuide/HowToAddNewLanguage.md)
(if applicable)
- [ ] I have performed a self-review of my own code
- [ ] My changes generate no new warnings

### Documentation

- [ ] I have updated relevant docs on [Stirling-PDF's doc
repo](https://github.com/Stirling-Tools/Stirling-Tools.github.io/blob/main/docs/)
(if functionality has heavily changed)
- [ ] I have read the section [Add New Translation
Tags](https://github.com/Stirling-Tools/Stirling-PDF/blob/main/devGuide/HowToAddNewLanguage.md#add-new-translation-tags)
(for new translation tags only)

### UI Changes (if applicable)

- [ ] Screenshots or videos demonstrating the UI changes are attached
(e.g., as comments or direct attachments in the PR)

### Testing (if applicable)

- [ ] I have tested my changes locally. Refer to the [Testing
Guide](https://github.com/Stirling-Tools/Stirling-PDF/blob/main/devGuide/DeveloperGuide.md#6-testing)
for more details.

frontend/src/core/contexts/ViewerContext.tsx

@@ -117,11 +117,13 @@ interface ViewerContextType {
   registerImmediateZoomUpdate: (callback: (percent: number) => void) => () => void;
   registerImmediateScrollUpdate: (callback: (currentPage: number, totalPages: number) => void) => () => void;
   registerImmediateSpreadUpdate: (callback: (mode: SpreadMode, isDualPage: boolean) => void) => () => void;
+  registerImmediatePanUpdate: (callback: (isPanning: boolean) => void) => () => void;
 
   // Internal - for bridges to trigger immediate updates
   triggerImmediateScrollUpdate: (currentPage: number, totalPages: number) => void;
   triggerImmediateZoomUpdate: (zoomPercent: number) => void;
   triggerImmediateSpreadUpdate: (mode: SpreadMode, isDualPage?: boolean) => void;
+  triggerImmediatePanUpdate: (isPanning: boolean) => void;
 
   // Action handlers - call EmbedPDF APIs directly
   scrollActions: ScrollActions;
@@ -140,6 +142,10 @@ interface ViewerContextType {
     type: K,
     ref: BridgeRef<BridgeStateMap[K], BridgeApiMap[K]>
   ) => void;
+
+  // Save changes function - registered by EmbedPdfViewer
+  applyChanges: (() => Promise<void>) | null;
+  setApplyChanges: (fn: (() => Promise<void>) | null) => void;
 }
 
 export const ViewerContext = createContext<ViewerContextType | null>(null);
@@ -163,6 +169,19 @@ export const ViewerProvider: React.FC<ViewerProviderProps> = ({ children }) => {
   // Bridge registry - bridges register their state and APIs here
   const bridgeRefs = useRef<ViewerBridgeRegistry>(createBridgeRegistry());
 
+  // Apply changes function - registered by EmbedPdfViewer
+  const applyChangesRef = useRef<(() => Promise<void>) | null>(null);
+  
+  const setApplyChanges = useCallback((fn: (() => Promise<void>) | null) => {
+    applyChangesRef.current = fn;
+  }, []);
+  
+  const applyChanges = useCallback(async () => {
+    if (applyChangesRef.current) {
+      await applyChangesRef.current();
+    }
+  }, []);
+
   const {
     register: registerImmediateZoomUpdate,
     trigger: triggerImmediateZoomInternal,
@@ -175,6 +194,10 @@ export const ViewerProvider: React.FC<ViewerProviderProps> = ({ children }) => {
     register: registerImmediateSpreadUpdate,
     trigger: triggerImmediateSpreadInternal,
   } = useImmediateNotifier<[SpreadMode, boolean]>();
+  const {
+    register: registerImmediatePanUpdate,
+    trigger: triggerImmediatePanInternal,
+  } = useImmediateNotifier<[boolean]>();
 
   const triggerImmediateZoomUpdate = useCallback(
     (percent: number) => {
@@ -197,6 +220,13 @@ export const ViewerProvider: React.FC<ViewerProviderProps> = ({ children }) => {
     [triggerImmediateSpreadInternal]
   );
 
+  const triggerImmediatePanUpdate = useCallback(
+    (isPanning: boolean) => {
+      triggerImmediatePanInternal(isPanning);
+    },
+    [triggerImmediatePanInternal]
+  );
+
   const registerBridge = useCallback(
     <K extends BridgeKey>(
       type: K,
@@ -335,9 +365,11 @@ export const ViewerProvider: React.FC<ViewerProviderProps> = ({ children }) => {
     registerImmediateZoomUpdate,
     registerImmediateScrollUpdate,
     registerImmediateSpreadUpdate,
+    registerImmediatePanUpdate,
     triggerImmediateScrollUpdate,
     triggerImmediateZoomUpdate,
     triggerImmediateSpreadUpdate,
+    triggerImmediatePanUpdate,
 
     // Actions
     scrollActions,
@@ -353,6 +385,10 @@ export const ViewerProvider: React.FC<ViewerProviderProps> = ({ children }) => {
 
     // Bridge registration
     registerBridge,
+
+    // Apply changes
+    applyChanges,
+    setApplyChanges,
   };
 
   return (