**Reserve and price**: technological reserve in percentage (default 10%),
optionally price per tile and number of tiles in a box to calculate the required
boxes and total price.
- **Visualization**: `FloorView` (custom View) draws a scaled diagram of
the floor with the corresponding arrangement pattern.
- **History**: calculations can be saved in a local SQLite database
(`DatabaseHelper`) and view/delete them from a separate screen.
## Calculation formula in brief
1. Number of tiles by width/length = rounded up (room size /
(tile size + joint)).
2. Tiles needed (net) = columns × rows.
3. Total reserve = user-entered reserve + model allowance
(0% for grid, 5% for brick, 15% for diagonal).
4. Tiles to order = rounded up (net tiles × (1 + reserve / 100)).
5. Boxes = rounded up (tiles per order / tiles per box), if
set.