refactor: update PDF comparison types and enhance UI for better usability

- Refactored CompareState to import from a centralized type definition.
- Enhanced the compare-pdfs.html layout with improved styles for overlay and side-by-side modes.
- Added new CSS styles for various UI components including panels, buttons, and highlights.
- Implemented a new sidebar for displaying change summaries and filters.
- Created unit tests for text comparison logic, including diffing text runs and page pairing.
- Added tests for text normalization functions to ensure proper handling of punctuation and character normalization.

src/js/types/compare-pdfs-type.ts

@@ -1,9 +1 @@
-import * as pdfjsLib from 'pdfjs-dist';
-
-export interface CompareState {
-    pdfDoc1: pdfjsLib.PDFDocumentProxy | null;
-    pdfDoc2: pdfjsLib.PDFDocumentProxy | null;
-    currentPage: number;
-    viewMode: 'overlay' | 'side-by-side';
-    isSyncScroll: boolean;
-}
+export type { CompareState } from '../compare/types.ts';