fix: address Storybook review findings

src/lib/ui/components/IconButton.svelte

@@ -1,20 +1,33 @@
 <script lang="ts">
+  import type { HTMLButtonAttributes } from "svelte/elements";
   import IconGlyph from "./IconGlyph.svelte";
 
+  type IconButtonProps = Omit<HTMLButtonAttributes, "type"> & {
+    icon: string;
+    label: string;
+    active?: boolean;
+    type?: "button" | "submit" | "reset";
+  };
+
   let {
     icon,
     label,
     active = false,
     disabled = false,
-  }: {
-    icon: string;
-    label: string;
-    active?: boolean;
-    disabled?: boolean;
-  } = $props();
+    type = "button",
+    class: className = "",
+    ...buttonProps
+  }: IconButtonProps = $props();
 </script>
 
-<button class="icon-button" aria-label={label} data-active={active} {disabled}>
+<button
+  {...buttonProps}
+  class={className ? `icon-button ${className}` : "icon-button"}
+  aria-label={label}
+  data-active={active}
+  {disabled}
+  {type}
+>
   <IconGlyph name={icon} size="sm" />
 </button>