Fixed: Links not working in restored tabs after closing all tabs and restoring them.

* Improved the tab closing and restoring process. Previously, when the user closed all tabs, the `ZimFileReader` was set to null. If the user restored the tabs, a new `ZimFileReader` was created, which was a resource-intensive operation, especially for large ZIM files.
* Now, the `ZimFileReader` is not set to null while the "restore tab" snackbar is visible, allowing users to restore tabs without recreating the ZimFileReader.
* Once the snackbar is dismissed, the `ZimFileReader` is set to null to free up resources since it is no longer required.

app/src/main/java/org/kiwix/kiwixmobile/nav/destination/reader/KiwixReaderFragment.kt

@@ -159,12 +159,25 @@ class KiwixReaderFragment : CoreReaderFragment() {
   override fun openHomeScreen() {
     Handler(Looper.getMainLooper()).postDelayed({
       if (webViewList.size == 0) {
-        hideTabSwitcher()
+        hideTabSwitcher(false)
       }
     }, HIDE_TAB_SWITCHER_DELAY)
   }
 
-  override fun hideTabSwitcher() {
+  /**
+   * Hides the tab switcher and optionally closes the ZIM book based on the `shouldCloseZimBook` parameter.
+   *
+   * @param shouldCloseZimBook If `true`, the ZIM book will be closed, and the `ZimFileReader` will be set to `null`.
+   * If `false`, it skips setting the `ZimFileReader` to `null`. This is particularly useful when restoring tabs,
+   * as setting the `ZimFileReader` to `null` would require re-creating it, which is a resource-intensive operation,
+   * especially for large ZIM files.
+   *
+   * Refer to the following methods for more details:
+   * @See exitBook
+   * @see closeTab
+   * @see closeAllTabs
+   */
+  override fun hideTabSwitcher(shouldCloseZimBook: Boolean) {
     actionBar?.let { actionBar ->
       actionBar.setDisplayShowTitleEnabled(true)
       toolbar?.let { activity?.setupDrawerToggle(it, true) }
@@ -181,7 +194,7 @@ class KiwixReaderFragment : CoreReaderFragment() {
       }
       mainMenu?.showWebViewOptions(true)
       if (webViewList.isEmpty()) {
-        exitBook()
+        exitBook(shouldCloseZimBook)
       } else {
         // Reset the top margin of web views to 0 to remove any previously set margin
         // This ensures that the web views are displayed without any additional

core/src/main/java/org/kiwix/kiwixmobile/core/main/CoreReaderFragment.kt

@@ -860,7 +860,13 @@ abstract class CoreReaderFragment :
     view?.startAnimation(AnimationUtils.loadAnimation(view.context, anim))
   }
 
-  protected open fun hideTabSwitcher() {
+  /**
+   * @param shouldCloseZimBook A flag to indicate whether the ZIM book should be closed.
+   *        - Default is `true`, which ensures normal behavior for most scenarios.
+   *        - If `false`, the ZIM book is not closed. This is useful in cases where the user restores tabs,
+   *          as closing the ZIM book would require reloading the ZIM file, which can be a resource-intensive operation.
+   */
+  protected open fun hideTabSwitcher(shouldCloseZimBook: Boolean = true) {
     actionBar?.apply {
       setDisplayShowTitleEnabled(true)
     }
@@ -1388,7 +1394,17 @@ abstract class CoreReaderFragment :
         .setAction(R.string.undo) { undoButton ->
           undoButton.isEnabled = false
           restoreDeletedTab(index)
-        }.show()
+        }.addCallback(object : Snackbar.Callback() {
+          override fun onDismissed(transientBottomBar: Snackbar?, event: Int) {
+            super.onDismissed(transientBottomBar, event)
+            // If the undo button is not clicked and no tabs are left, exit the book and
+            // clean up resources.
+            if (event != DISMISS_EVENT_ACTION && webViewList.isEmpty()) {
+              closeZimBook()
+            }
+          }
+        })
+        .show()
     }
     openHomeScreen()
   }
@@ -1399,18 +1415,20 @@ abstract class CoreReaderFragment :
     mainMenu?.showBookSpecificMenuItems()
   }
 
-  protected fun exitBook() {
+  protected fun exitBook(shouldCloseZimBook: Boolean = true) {
     showNoBookOpenViews()
     bottomToolbar?.visibility = View.GONE
     actionBar?.title = getString(R.string.reader)
     contentFrame?.visibility = View.GONE
     hideProgressBar()
     mainMenu?.hideBookSpecificMenuItems()
-    closeZimBook()
+    if (shouldCloseZimBook) {
+      closeZimBook()
+    }
   }
 
   fun closeZimBook() {
-    coreReaderLifeCycleScope?.launch {
+    lifecycleScope.launch {
       zimReaderContainer?.setZimReaderSource(null)
     }
   }
@@ -1445,7 +1463,6 @@ abstract class CoreReaderFragment :
           LinearLayout.LayoutParams.MATCH_PARENT
         )
       }
-      // zimReaderContainer?.setZimReaderSource(tempZimSourceForUndo)
       webViewList.add(index, it)
       tabsAdapter?.notifyDataSetChanged()
       snackBarRoot?.let { root ->
@@ -1878,7 +1895,16 @@ abstract class CoreReaderFragment :
           setIsCloseAllTabButtonClickable(true)
           restoreDeletedTabs()
         }
-      }.show()
+      }.addCallback(object : Snackbar.Callback() {
+        override fun onDismissed(transientBottomBar: Snackbar?, event: Int) {
+          super.onDismissed(transientBottomBar, event)
+          // If the undo button is not clicked and no tabs are left, exit the book and
+          // clean up resources.
+          if (event != DISMISS_EVENT_ACTION && webViewList.isEmpty()) {
+            closeZimBook()
+          }
+        }
+      }).show()
     }
   }
 
@@ -1888,7 +1914,6 @@ abstract class CoreReaderFragment :
 
   private fun restoreDeletedTabs() {
     if (tempWebViewListForUndo.isNotEmpty()) {
-      // zimReaderContainer?.setZimReaderSource(tempZimSourceForUndo)
       webViewList.addAll(tempWebViewListForUndo)
       tabsAdapter?.notifyDataSetChanged()
       snackBarRoot?.let { root ->