Epub improvements (#160)

* Improved navigation and search result highlighting in the EPUB reader

* refactor: implement JIT chunk restoration for robust navigation

- Fixes search and bookmark navigation failing in same-chapter transitions.
- Introduced JIT (Just-in-Time) HTML restoration in `epub_reader.js` to
  re-populate virtualized chunks before CFI resolution or search scrolling.
- Synchronized search highlighting and user highlights within
  newly-restored chunk segments.
- Improved search navigation accuracy by mapping occurrences to
  relative chunk indices.

* Implemented a custom text selection engine for the paginated EPUB reader to support cross-page selection and improved handle interaction.

* Implemented management of external file behavior and improved library filtering.

* Added support for toolbar customization in the EPUB reader.

* Added support for toolbar customization in the PDF reader.

* fix: rendering during auto-scroll and navigation on long pages

* Added a "Scroll to Top" feature to the auto-scroll controls in both EPUB and PDF readers.

app/src/main/java/com/aryan/reader/MainActivity.kt

@@ -105,7 +105,7 @@ class MainActivity : ComponentActivity() {
         if (intent?.action == Intent.ACTION_VIEW && intent.data != null) {
             Timber.d("Received VIEW intent with URI: ${intent.data}")
             val uri = intent.data!!
-            viewModel.onFileSelected(uri)
+            viewModel.onFileSelected(uri, isFromRecent = false, isExternalIntent = true)
         }
     }
 }