added number conversion in HTML value retrieval

Changes:
- number input fields now return numbers
- range elements removed since they are untested

Additions:
- added min and step specifiers to input fields associated to
  item number properties
- added a color hint for invalidity of
  item number input fields in actor sheet

src/scss/components/_items.scss

@@ -1,3 +1,5 @@
+@use "sass:color";
+
 .items-list {
     list-style: none;
     margin: 7px 0;
@@ -52,6 +54,9 @@
         width: 2.5em;
         padding: 0;
     }
+    .item-num-val:invalid {
+        background-color: color.mix(lightcoral, $c-light-grey, 25%);
+    }
 
     .item-description {
         font-size: 75%;