fix(mood): make the slider clear affordance an icon, not a text label

The clear-action button sat as muted text beside the value, so a set
slider read as one phrase — the number fused with the word next to it
(a value of 4 next to "leeren" showed as "4 leeren"). Replace it with
an icon-only X that carries the same label as its accessible name, so
the value readout stays the bare number in every locale at once.

src/components/ui/__tests__/slider.test.tsx

@@ -105,7 +105,11 @@ describe("<SliderField>", () => {
   it("offers to clear an answer only when there is one to clear", () => {
     const set = field({ onClear: () => {}, clearLabel: "zurücksetzen" });
     expect(set).toContain('data-slot="slider-field-clear"');
-    expect(set).toContain("zurücksetzen");
+    // The clear affordance is icon-only: the label rides the accessible name,
+    // not visible text beside the value, so a set slider never reads "4 leeren".
+    expect(set).toContain('aria-label="zurücksetzen"');
+    // The value span holds only the bare number, never the clear-action label.
+    expect(set).toMatch(/data-slot="slider-field-value"[^>]*>7<\/span>/);
 
     const unanswered = field({
       value: null,

src/components/ui/slider.tsx

@@ -2,6 +2,7 @@
 
 import * as React from "react";
 import { Slider as SliderPrimitive } from "radix-ui";
+import { X } from "lucide-react";
 
 import { cn } from "@/lib/utils";
 
@@ -136,9 +137,11 @@ function SliderField({
               type="button"
               onClick={onClear}
               data-slot="slider-field-clear"
-              className="text-muted-foreground hover:text-foreground focus-visible:ring-ring/50 rounded text-xs underline-offset-2 outline-none hover:underline focus-visible:ring-[3px]"
+              aria-label={clearLabel}
+              className="text-muted-foreground hover:text-foreground focus-visible:ring-ring/50 flex size-6 items-center justify-center rounded outline-none focus-visible:ring-[3px]"
             >
-              {clearLabel}
+              <X className="size-3.5" aria-hidden="true" />
+              <span className="sr-only">{clearLabel}</span>
             </button>
           ) : null}
         </span>