Refactor Cart into checkerboard table

Closes: #173 (closed)

Removes clear all feature from: #233

This one improves focus behavior in the cart, moving cart items and deleting items from the cart.

clive/__private/ui/operations/cart.py

 from __future__ import annotations
 
-from typing import TYPE_CHECKING
+from typing import TYPE_CHECKING, Sequence
 
 from textual import on
 from textual.binding import Binding
@@ -214,34 +214,38 @@ class Cart(BaseScreen):
     async def __rebuild_items(self, from_index: int = 0, to_index: int | None = None) -> None:
         await self._cart_table.rebuild(starting_from_element=from_index, ending_with_element=to_index)
 
-    def _devalue_indexes_and_readjust_styles_after_remove(self, triggering_widget: CartItem) -> None:
+    def _handle_remove_event(self, triggering_widget: CartItem) -> None:
+        def devalue_indexes(rows: Sequence[CartItem]) -> None:
+            for row in rows:
+                row.reactive_idx = row.idx - 1
+
         start_index = triggering_widget.idx
-        end_index = len(self.app.world.profile_data.cart)
-        rows = self.query(CartItem)[start_index:end_index]
-        for row in rows:
-            row.reactive_idx = row.idx - 1
+        rows = self.query(CartItem)[start_index:]
+        devalue_indexes(rows)
         self._cart_table.set_evenness_styles(rows, starting_index=start_index)
 
     def _update_values_of_swapped_rows(self, from_index: int, to_index: int) -> None:
         def get_cells_with_values(row_index: int) -> tuple[list[CliveCheckerBoardTableCell], list[str | Widget]]:
             row = self.query(CartItem)[row_index]
-            cells = row.query(CliveCheckerBoardTableCell)[1:-1]  # exclude index and horizontal with buttons
+            start_index = 1  # exclude value of first cell - index
+            end_index = -1  # exclude value of last cell - horizontal with buttons
+            cells = row.query(CliveCheckerBoardTableCell)[start_index:end_index]
             data = [cell.content for cell in cells]
             return cells, data
 
         from_cells, from_data = get_cells_with_values(from_index)
         to_cells, to_data = get_cells_with_values(to_index)
 
-        for x in (to_cells, from_data), (from_cells, to_data):
-            for cell, value in zip(x[0], x[1]):
-                cell.update_content(value)
+        for cells, data in [(to_cells, from_data), (from_cells, to_data)]:
+            for cell, value in zip(cells, data):
+                cell.update_content(value)  # type: ignore[arg-type]
 
     @on(CartItem.Delete)
     async def remove_item(self, event: CartItem.Delete) -> None:
         self.app.world.profile_data.cart.remove(event.widget.operation)
         self.app.trigger_profile_data_watchers()
         await self.query(CliveCheckerboardTableRow)[event.widget.idx].remove()
-        self._devalue_indexes_and_readjust_styles_after_remove(triggering_widget=event.widget)
+        self._handle_remove_event(triggering_widget=event.widget)
 
         if len(self.app.world.profile_data.cart) > 0 and event.widget.idx == 0:
             # disable first ButtomMoveUp if first element was removed
@@ -252,8 +256,10 @@ class Cart(BaseScreen):
 
     @on(CartItem.Move)
     async def move_item(self, event: CartItem.Move) -> None:
-        assert event.to_idx >= 0
-        assert event.to_idx < len(self.app.world.profile_data.cart)
+        assert event.to_idx >= 0, "Item cannot be moved to id lower than 0."
+        assert event.to_idx < len(
+            self.app.world.profile_data.cart
+        ), "Item cannot be moved to id greater than cart length."
 
         self.app.world.profile_data.cart.swap(event.from_idx, event.to_idx)
         self.app.trigger_profile_data_watchers()