Refactor and enhance type safety across various modules

- Updated function parameters and return types in `page-preview.ts`, `pdf-decrypt.ts`, and `pymupdf-loader.ts` for improved type safety.
- Introduced type definitions for `CpdfInstance`, `PyMuPDFInstance`, and other related types to ensure better type checking.
- Enhanced error handling in `sanitize.ts` by creating a utility function for error messages.
- Removed unnecessary type assertions and improved type inference in `editor.ts`, `serialization.ts`, and `tools.test.ts`.
- Added type definitions for markdown-it plugins to improve compatibility and type safety.
- Enforced stricter TypeScript settings by enabling `noImplicitAny` in `tsconfig.json`.
- Cleaned up test files by refining type assertions and ensuring consistency in type usage.

src/js/compare/engine/compare.worker.ts

@@ -4,7 +4,6 @@ import type {
   CompareTextItem,
   ComparePageSignature,
   ComparePagePair,
-  ComparePageResult,
   CompareChangeSummary,
   CompareTextChange,
 } from '../types.ts';
@@ -44,8 +43,6 @@ interface ErrorResult {
   message: string;
 }
 
-type WorkerResult = DiffResult | PairResult | ErrorResult;
-
 self.onmessage = function (e: MessageEvent<WorkerMessage>) {
   const msg = e.data;
   try {