Feature/v2/saved signatures (#4899)

Add Saved signature functionality

frontend/src/core/constants/app.ts

@@ -3,6 +3,11 @@
 // When no subpath, use empty string instead of '.' to avoid relative path issues
 export const BASE_PATH = (import.meta.env.BASE_URL || '/').replace(/\/$/, '').replace(/^\.$/, '');
 
+// EmbedPDF needs time to remove annotations internally before a recreation runs.
+// Without the buffer we occasionally end up with duplicate annotations or stale image data.
+export const ANNOTATION_RECREATION_DELAY_MS = 50;
+export const ANNOTATION_VERIFICATION_DELAY_MS = 100;
+
 /** For in-app navigations when you must touch window.location (rare). */
 export const withBasePath = (path: string): string => {
   const clean = path.startsWith('/') ? path : `/${path}`;