refactor: align tooltip variants with Figma design system

Replace variant prop (default/small/large) with size prop (small/large)
to match Figma component properties. Remove default variant that was
replicating PrimeVue Aura styling. Extract shared styles into cva base.

src/components/ui/tooltip/BaseTooltip.vue

@@ -17,7 +17,7 @@ const {
   text = '',
   side = 'top',
   sideOffset = 4,
-  variant = 'default',
+  size = 'small',
   delayDuration,
   disabled = false,
   class: className
@@ -25,7 +25,7 @@ const {
   text?: string
   side?: 'top' | 'bottom' | 'left' | 'right'
   sideOffset?: number
-  variant?: NonNullable<TooltipVariants['variant']>
+  size?: NonNullable<TooltipVariants['size']>
   delayDuration?: number
   disabled?: boolean
   class?: HTMLAttributes['class']
@@ -41,11 +41,10 @@ const {
       <TooltipContent
         :side="side"
         :side-offset="sideOffset"
-        :class="cn(tooltipVariants({ variant }), className)"
+        :class="cn(tooltipVariants({ size }), className)"
       >
         {{ text }}
         <TooltipArrow
-          v-if="variant !== 'default'"
           :width="8"
           :height="5"
           class="fill-node-component-tooltip-surface"

src/components/ui/tooltip/tooltip.variants.ts

@@ -2,18 +2,15 @@ import type { VariantProps } from 'cva'
 import { cva } from 'cva'
 
 export const tooltipVariants = cva({
-  base: 'z-50 select-none',
+  base: 'z-50 select-none border border-node-component-tooltip-border bg-node-component-tooltip-surface px-4 py-2 text-node-component-tooltip shadow-none',
   variants: {
-    variant: {
-      default: 'rounded-md bg-[#3f3f46] px-3 py-2 text-sm text-white shadow-sm',
-      small:
-        'rounded-lg border border-node-component-tooltip-border bg-node-component-tooltip-surface px-4 py-2 text-xs text-node-component-tooltip shadow-none',
-      large:
-        'max-w-75 rounded-sm border border-node-component-tooltip-border bg-node-component-tooltip-surface px-4 py-2 text-sm/tight font-normal text-node-component-tooltip shadow-none'
+    size: {
+      small: 'rounded-lg text-xs',
+      large: 'max-w-75 rounded-sm text-sm/tight font-normal'
     }
   },
   defaultVariants: {
-    variant: 'default'
+    size: 'small'
   }
 })