style: cleanup formatting and code style across the project

Clean up formatting and code style across the project.

- Remove unnecessary whitespace and empty lines in `src/model/cell.rs` ,
  `src/model/types.rs` , and `src/draw.rs` .
- Reformat long lines and function calls in `src/command/cmd.rs` ,
  `src/ui/grid.rs` , and `src/ui/tile_bar.rs` for better readability.
- Consolidate imports and simplify expressions in `src/command/keymap.rs` and
  `src/ui/app.rs` .

Co-Authored-By: fiddlerwoaroof/git-smart-commit (unsloth/gemma-4-26B-A4B-it-GGUF:UD-Q5_K_XL)

src/model/types.rs

@@ -132,8 +132,7 @@ impl Model {
             self.data.remove(&k);
         }
         // Remove formulas targeting this category
-        self.formulas
-            .retain(|f| f.target_category != name);
+        self.formulas.retain(|f| f.target_category != name);
     }
 
     /// Remove an item from a category and all cells that reference it.