fix(tooltip): drop the caret shadow — it smudged onto the panel

A single-direction drop-shadow on the caret is wrong: the caret sits at the panel
edge pointing AT the trigger, so on a bottom-side tooltip (caret at the top) the
downward shadow falls onto the panel below it — a dark smudge over the content.
Remove it. The caret keeps the panel-bg fill + border edges (no black blob, no
smudge). A shadow that reads correctly would have to wrap the whole panel+caret
silhouette (content-level drop-shadow), not the caret alone.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

src/uix/eidos/components/tooltip/tooltip.css

@@ -103,13 +103,6 @@
 	vector-effect: non-scaling-stroke;
 }
 
-/* The caret shares the panel bg, so it needs its own soft shadow to read against
- * the page — the panel's box-shadow is rectangular and stops at the panel edge, so
- * it never reaches the caret. `drop-shadow` follows the triangle's silhouette. */
-[data-tooltip-arrow] {
-	filter: drop-shadow(0 1px 1.5px color-mix(in srgb, var(--tooltip-color) 35%, transparent));
-}
-
 /* Outline variant: transparent bg → fill with the surface, stroke the edges. */
 [data-tooltip-content][data-variant='outline'] ~ [data-tooltip-arrow] polygon,
 [data-tooltip-content][data-variant='outline'] [data-tooltip-arrow] polygon {