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>

docs/sw/followup-four-qa/reference/Rectangle 6926.svg

@@ -0,0 +1,11 @@
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+<path d="M2.96798 0.5H57.032C58.395 0.5 59.5 1.60495 59.5 2.96798C59.5 4.331 58.395 5.43595 57.032 5.43595H2.96798C1.60495 5.43595 0.5 4.331 0.5 2.96798C0.5 1.60495 1.60495 0.5 2.96798 0.5Z" fill="url(#paint0_linear_26_12080)" stroke="black"/>
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+<stop stop-color="#8E0000"/>
+<stop offset="0.370561" stop-color="#FF4242"/>
+<stop offset="0.76" stop-color="#E40000"/>
+<stop offset="1" stop-color="#1E0000"/>
+</linearGradient>
+</defs>
+</svg>