fix(emcn): stop the combobox cursor diverging from what Enter commits

The option rows painted --surface-active from CSS :hover as well as from
isHighlighted. CSS :hover tracks the pointer continuously while highlightedIndex
only advances on mouseenter, so once the list scrolled under a stationary
pointer the row that looked selected was not the one Enter would commit —
Enter reads filteredOptions[highlightedIndex].

isHighlighted is now the single source of truth for the cursor, so paint and
commit cannot disagree. The row under a stationary pointer may lag a scroll
until the mouse moves, but it lags in agreement with what Enter will do, which
is the invariant worth keeping. Disabled options also stop painting on hover,
matching the mouseenter guard that already refused to highlight them.

The 'All' row keeps its own hover: it clears the highlight rather than taking
it, so it has no isHighlighted paint to fall back on.

Author: waleedlatif1

packages/emcn/src/components/combobox/combobox.tsx

@@ -151,14 +151,6 @@ export interface ComboboxProps
   emptyMessage?: string
 }
 
-/**
- * Option cursor, not a hover affordance: it matches the keyboard highlight, so it
- * keeps `--surface-active` rather than the dimmer `chipHoverSurfaceClass` rows
- * use. Kept alongside `isHighlighted` because `onMouseEnter` does not re-fire
- * when the list scrolls under a stationary pointer.
- */
-const OPTION_CURSOR_CLASS = 'hover-hover:bg-[var(--surface-active)]'
-
 /**
  * Minimal combobox component matching the input and textarea styling.
  * Provides a dropdown selection interface with keyboard navigation support.
@@ -850,7 +842,16 @@ const Combobox = memo(
                                 className={cn(
                                   'relative flex cursor-pointer select-none items-center gap-2 rounded-sm px-1.5 font-sans',
                                   size === 'sm' ? 'py-[5px] text-caption' : 'py-1.5 text-sm',
-                                  OPTION_CURSOR_CLASS,
+                                  /*
+                                     No CSS `:hover` here — `isHighlighted` is the
+                                     single source of truth for the cursor, because
+                                     it is also what Enter commits. A `:hover` class
+                                     tracks the pointer continuously while
+                                     `highlightedIndex` only moves on `mouseenter`,
+                                     so after the list scrolls under a stationary
+                                     pointer the two disagree and the row that looks
+                                     selected is not the one Enter would choose.
+                                  */
                                   (isHighlighted || isSelected) && chipActiveSurfaceClass,
                                   option.disabled && 'cursor-not-allowed opacity-50'
                                 )}
@@ -926,7 +927,7 @@ const Combobox = memo(
                             className={cn(
                               'relative flex cursor-pointer select-none items-center gap-2 rounded-sm px-1.5 font-sans',
                               size === 'sm' ? 'py-[5px] text-caption' : 'py-1.5 text-sm',
-                              OPTION_CURSOR_CLASS,
+                              // See above: `isHighlighted` alone, so paint matches what Enter commits.
                               (isHighlighted || isSelected) && chipActiveSurfaceClass,
                               option.disabled && 'cursor-not-allowed opacity-50'
                             )}