feat: support decimals in position quantity input

closes issue #12

src/components/Settings/Positions.tsx

@@ -244,23 +244,23 @@ export const PositionsSettings: Component = () => {
                             <div class="flex-1">
                               <input
                                 class="w-full input input-bordered input-xs"
-                                value={
+                                value={position.quantity}
-                                  position.quantity === 0
-                                    ? ""
-                                    : position.quantity
-                                }
                                 placeholder="Menge"
                                 min="0"
+                                step="0.01"
                                 required
                                 type="number"
-                                onInput={(e) => {
+                                lang="en"
+                                onInput={createOptionalNumberInputHandler(
+                                  (v) => {
                                     setState(
                                       "positions",
                                       idx(),
                                       "quantity",
-                                    parseFloat(e.currentTarget.value) || 0
+                                      v || 0
                                     );
-                                }}
+                                  }
+                                )}
                               />
                             </div>
                           </Show>