fix: stop paging up or down on a single row table from crashing

page_up and page_down wrap the selection with a modulus of items_len - 1,
which is a remainder by zero when the table holds exactly one row. Ctrl-U
or Ctrl-D on such a table panicked the TUI. Both now return early for
tables of one row or fewer, mirroring the existing empty-table guard;
tables of two or more rows keep their existing paging arithmetic.

src/models/stateful_table.rs

@@ -100,7 +100,7 @@ where
 {
   fn page_down(&mut self) {
     let items_len = self.active_items().len();
-    if items_len == 0 {
+    if items_len <= 1 {
       return;
     }
 
@@ -113,7 +113,7 @@ where
 
   fn page_up(&mut self) {
     let items_len = self.active_items().len();
-    if items_len == 0 {
+    if items_len <= 1 {
       return;
     }
 

src/models/stateful_table_tests.rs

@@ -239,6 +239,59 @@ mod tests {
     );
   }
 
+  #[test]
+  fn test_stateful_table_pagination_on_single_item_table_performs_no_op() {
+    let mut stateful_table: StatefulTable<String> = StatefulTable::default();
+    stateful_table.set_items(vec!["Test 1".to_owned()]);
+
+    assert_some_eq_x!(stateful_table.state.selected(), 0);
+
+    stateful_table.page_down();
+
+    assert_some_eq_x!(stateful_table.state.selected(), 0);
+
+    stateful_table.page_up();
+
+    assert_some_eq_x!(stateful_table.state.selected(), 0);
+  }
+
+  #[test]
+  fn test_stateful_table_filtered_pagination_on_single_item_table_performs_no_op() {
+    let mut filtered_stateful_table: StatefulTable<String> = StatefulTable::default();
+    filtered_stateful_table.set_filtered_items(vec!["Test 1".to_owned()]);
+
+    assert_some_eq_x!(
+      filtered_stateful_table
+        .filtered_state
+        .as_ref()
+        .unwrap()
+        .selected(),
+      0
+    );
+
+    filtered_stateful_table.page_down();
+
+    assert_some_eq_x!(
+      filtered_stateful_table
+        .filtered_state
+        .as_ref()
+        .unwrap()
+        .selected(),
+      0
+    );
+
+    filtered_stateful_table.page_up();
+
+    assert_some_eq_x!(
+      filtered_stateful_table
+        .filtered_state
+        .as_ref()
+        .unwrap()
+        .selected(),
+      0
+    );
+  }
+
   #[test]
   fn test_stateful_table_pagination() {
     let mut stateful_table = StatefulTable::default();