Fix non-first morpheme form cell stealing focus to gloss input

Clicking a span (non-first) form cell in MorphemeBox bubbled its
mousedown up to TokenChip's label handler, which only recognizes
input/button targets and so treated the span as unhandled, focusing
the gloss input before the popover opened.

Author: imnasnainaec

src/components/MorphemeBox.tsx

@@ -118,8 +118,11 @@ export function MorphemeBox({
               key={m.id}
               aria-hidden="true"
               className={formClassName}
-              style={formStyle}
               onClick={handleClick}
+              // Not a button, so stop mousedown from bubbling to TokenChip's label handler (which
+              // would otherwise focus the gloss input).
+              onMouseDown={(e) => e.stopPropagation()}
+              style={formStyle}
             >
               {m.form}
             </span>

src/components/TokenChip.tsx

@@ -167,8 +167,10 @@ export function TokenChip({
    * The input is looked up by id rather than `querySelector('input')` because the morpheme gloss
    * inputs precede it inside the label when morphology is shown. A mouse-down on any input is left
    * to that input's own handling ({@link handleMouseDown} for the gloss input, which bubbles here
-   * after already handling it); a mouse-down on a morpheme form cell or the unanalyzed "define"
-   * trigger (all `button`s) is left to that button's own click handler, which opens the popover.
+   * after already handling it); a mouse-down on the first morpheme form cell or the unanalyzed
+   * "define" trigger (both real `button`s) is left to that button's own click handler. The
+   * remaining morpheme form cells are `span`s that stop their own mousedown from bubbling here
+   * instead (see {@link MorphemeBox}).
    *
    * @param e - The label's mouse-down event.
    */