fix(sw): refine property panel and Firefox range styles

- Property bar ends after its last field (content width, scrolls when longer)
- Remove Figma canvas layers from property tool and close SVGs
- Suppress header field hover while the field's own dropdown is open
- Gauge: Figma red fill pill, beige track, Figma thumb SVG; shared
  paint for WebKit and Gecko (::-moz-range-*) so Firefox matches Chrome
- Story buttons for gauge external value / disabled / read-only
- Browser checks: follow-up fixes, Chrome vs Firefox range, close button

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

src/sw/sw-header.stories.tsx

@@ -1454,6 +1454,9 @@ function PropertyPanelDemo({ standalone = false }: { standalone?: boolean }) {
         <button onClick={() => setProperties(items => [...items].reverse())}>속성 순서 뒤집기</button>
         <button onClick={() => setProperties(items => items.map(item => item.id === "weight" ? { ...item, disabled: !item.disabled } : item))}>가중치 Disabled</button>
         <button onClick={() => setProperties(items => items.map(item => item.id === "layer" ? { ...item, readOnly: !item.readOnly } : item))}>레이어 ReadOnly</button>
+        <button onClick={() => setProperties(items => items.map(item => item.id === "opacity" ? { ...item, value: "0.8" } : item))}>투명도 외부 값 변경</button>
+        <button onClick={() => setProperties(items => items.map(item => item.id === "opacity" ? { ...item, disabled: !item.disabled } : item))}>투명도 Disabled</button>
+        <button onClick={() => setProperties(items => items.map(item => item.id === "opacity" ? { ...item, readOnly: !item.readOnly } : item))}>투명도 ReadOnly</button>
       </div>
       <p className="sw-story-log" data-property-log="" aria-live="polite">{log.join(" → ") || "Callback 없음"}</p>
       <pre className="sw-story-layer-state" data-property-state="">{JSON.stringify({ selection: selection.id, values: properties.map(item => [item.id, item.value]), expanded, open })}</pre>
@@ -1538,7 +1541,7 @@ export const PropertyBar: Story = {
   name: "Property Bar",
   parameters: { controls: { disable: true } },
   render: () => <StoryPage className="sw-story-followup"><StoryPageHeader kicker={KICKER} title="속성Bar · 동적 편집" description="Figma 26:10492. 속성창과 독립 열림, 동일 호스트 데이터. 수치는 Figma 예시이며 CAD 계산은 수행하지 않습니다." /><PropertyBarDemo />
-    <StorySection title="1222 × 28 기준"><div className="sw-story-scroller"><SWTheme><div style={{ width: 1222 }}><SWHeaderPropertyBar selection={{ id: "reference", title: "원", kind: "single" }} properties={BAR_FIXTURE} /></div></SWTheme></div></StorySection>
+    <StorySection title="콘텐츠 폭 기준 (부모 1222px, 높이 28)"><div className="sw-story-scroller"><SWTheme><div style={{ width: 1222 }}><SWHeaderPropertyBar selection={{ id: "reference", title: "원", kind: "single" }} properties={BAR_FIXTURE} /></div></SWTheme></div></StorySection>
   </StoryPage>,
 }