fix(tooltip): un-clip the caret — the real cause was overflow, not colour

The tooltip content is `position: relative; overflow: auto`, so the caret
(`position: absolute`, containing block = the content) that pokes past the panel
edge was CLIPPED away — invisible regardless of its colour. Confirmed by measuring:
the caret sits fully outside the content box, and the content clips its overflow.

Change the content to `overflow: visible` — the same reason the popover content is
`overflow: visible` (its comment literally says "fixes the arrow that overflow:auto
used to clip"). Tooltips are short, so no inner scroll viewport is needed.

Verified in a real browser: the dark caret is now clearly visible pointing at the
trigger. Combined with a40d1573 (caret colour back to currentColor) + the earlier
`display: block` (correct arrow height → correct trigger gap), the tooltip arrow is
visible and correctly placed again.

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

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

@@ -27,8 +27,11 @@
 	min-block-size: var(--_tooltip-content-min-height-override, auto);
 	max-block-size: var(--_tooltip-max-height);
 	padding: var(--_tooltip-py) var(--_tooltip-px);
-	overflow: auto;
-	overscroll-behavior: contain;
+	/* `visible` so the absolutely-positioned caret (containing block = this relative
+	 * content) is NOT clipped where it pokes past the panel edge — the same reason
+	 * the popover content is `overflow: visible`. Without this the arrow was clipped
+	 * away entirely. Tooltips are short, so no inner scroll viewport is needed. */
+	overflow: visible;
 	border: var(--tooltip-border-width) solid var(--_tooltip-border);
 	border-radius: var(--tooltip-radius);
 	background: var(--_tooltip-bg);