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/types/markdown-it-plugins.d.ts

@@ -0,0 +1,54 @@
+declare module 'markdown-it-sub' {
+  import type MarkdownIt from 'markdown-it';
+  const plugin: MarkdownIt.PluginSimple;
+  export default plugin;
+}
+
+declare module 'markdown-it-sup' {
+  import type MarkdownIt from 'markdown-it';
+  const plugin: MarkdownIt.PluginSimple;
+  export default plugin;
+}
+
+declare module 'markdown-it-footnote' {
+  import type MarkdownIt from 'markdown-it';
+  const plugin: MarkdownIt.PluginSimple;
+  export default plugin;
+}
+
+declare module 'markdown-it-deflist' {
+  import type MarkdownIt from 'markdown-it';
+  const plugin: MarkdownIt.PluginSimple;
+  export default plugin;
+}
+
+declare module 'markdown-it-abbr' {
+  import type MarkdownIt from 'markdown-it';
+  const plugin: MarkdownIt.PluginSimple;
+  export default plugin;
+}
+
+declare module 'markdown-it-emoji' {
+  import type MarkdownIt from 'markdown-it';
+  const plugin: MarkdownIt.PluginSimple;
+  export { plugin as full };
+  export default plugin;
+}
+
+declare module 'markdown-it-ins' {
+  import type MarkdownIt from 'markdown-it';
+  const plugin: MarkdownIt.PluginSimple;
+  export default plugin;
+}
+
+declare module 'markdown-it-mark' {
+  import type MarkdownIt from 'markdown-it';
+  const plugin: MarkdownIt.PluginSimple;
+  export default plugin;
+}
+
+declare module 'markdown-it-task-lists' {
+  import type MarkdownIt from 'markdown-it';
+  const plugin: MarkdownIt.PluginSimple;
+  export default plugin;
+}