Revert to native Tailwind utilities for tooltip styling

Changed from arbitrary values back to standard utilities:
- bg-[var(--color-popover)] → bg-popover
- text-[var(--color-popover-foreground)] → text-popover-foreground
- fill-[var(--color-popover)] → fill-popover
- Added explicit border-border for border color

These work with Tailwind v4's @theme directive where --color-* variables
automatically become available as utilities.

Author: kylecarbs

src/components/ui/tooltip.tsx

@@ -17,14 +17,13 @@ const TooltipContent = React.forwardRef<
     ref={ref}
     sideOffset={sideOffset}
     className={cn(
-      "z-50 overflow-hidden rounded-md border bg-[var(--color-popover)] px-2.5 py-1 text-xs text-[var(--color-popover-foreground)] shadow-md animate-in fade-in-0 zoom-in-95 data-[state=closed]:animate-out data-[state=closed]:fade-out-0 data-[state=closed]:zoom-out-95 data-[side=bottom]:slide-in-from-top-2 data-[side=left]:slide-in-from-right-2 data-[side=right]:slide-in-from-left-2 data-[side=top]:slide-in-from-bottom-2 origin-[--radix-tooltip-content-transform-origin]",
+      "z-50 overflow-hidden rounded-md border border-border bg-popover px-2.5 py-1 text-xs text-popover-foreground shadow-md animate-in fade-in-0 zoom-in-95 data-[state=closed]:animate-out data-[state=closed]:fade-out-0 data-[state=closed]:zoom-out-95 data-[side=bottom]:slide-in-from-top-2 data-[side=left]:slide-in-from-right-2 data-[side=right]:slide-in-from-left-2 data-[side=top]:slide-in-from-bottom-2 origin-[--radix-tooltip-content-transform-origin]",
       className
     )}
-    style={{ borderColor: "var(--color-border)" }}
     {...props}
   >
     {props.children}
-    <TooltipPrimitive.Arrow className="fill-[var(--color-popover)]" />
+    <TooltipPrimitive.Arrow className="fill-popover" />
   </TooltipPrimitive.Content>
 ));
 TooltipContent.displayName = TooltipPrimitive.Content.displayName;