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/components/viewer/RedactionPendingTracker.tsx

@@ -0,0 +1,41 @@
+import { useEffect, useRef, useImperativeHandle, forwardRef } from 'react';
+import { useRedaction as useEmbedPdfRedaction } from '@embedpdf/plugin-redaction/react';
+
+export interface RedactionPendingTrackerAPI {
+  commitAllPending: () => void;
+  getPendingCount: () => number;
+}
+
+/**
+ * RedactionPendingTracker monitors pending redactions and exposes an API
+ * for committing and checking pending redactions.
+ * Must be rendered inside the EmbedPDF context.
+ * 
+ * Note: The unsaved changes checker is registered by EmbedPdfViewer, not here,
+ * to avoid conflicts and allow the viewer to check both annotations and redactions.
+ */
+export const RedactionPendingTracker = forwardRef<RedactionPendingTrackerAPI>(
+  function RedactionPendingTracker(_, ref) {
+    const { state, provides } = useEmbedPdfRedaction();
+    
+    const pendingCountRef = useRef(0);
+    
+    // Expose API through ref
+    useImperativeHandle(ref, () => ({
+      commitAllPending: () => {
+        if (provides?.commitAllPending) {
+          provides.commitAllPending();
+        }
+      },
+      getPendingCount: () => pendingCountRef.current,
+    }), [provides]);
+    
+    // Update ref when pending count changes
+    useEffect(() => {
+      pendingCountRef.current = state?.pendingCount ?? 0;
+    }, [state?.pendingCount]);
+
+    return null;
+  }
+);
+