feat: paint variants drive header logo colour + bake in spec1=0 baseline

- Site-header .logo and quiz-progress-bar .qpb-logo now follow the
  active paint variant (currently green) and read --mod-fill so they
  track live changes from the modifier panel's fill picker. White
  paint is intentionally excluded — a near-white logo would vanish
  against the light header background. Applies on both mobile and
  desktop.

- Paint H1 default updated to spec1Const=0 in both paintGloss and
  paintGlossHover (matches the "Copy snippet" dump), removing the
  upper-left specular highlight from the dark paint baseline.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

src/App.vue

@@ -11,7 +11,7 @@
         <feComposite in="puddleShadowColor" in2="puddle" operator="in" result="puddleShadow"/>
         <feOffset in="puddleShadow" dx="0" dy="3" result="puddleShadowOff"/>
         <feGaussianBlur in="SourceAlpha" stdDeviation="1.4" result="bump"/>
-        <feSpecularLighting in="bump" surfaceScale="6" specularConstant="1.7"
+        <feSpecularLighting in="bump" surfaceScale="6" specularConstant="0"
                             specularExponent="28" lighting-color="#ffffff" result="spec">
           <fePointLight x="-300" y="-400" z="420"/>
         </feSpecularLighting>
@@ -42,7 +42,7 @@
         <feComposite in="puddleShadowColor" in2="puddle" operator="in" result="puddleShadow"/>
         <feOffset in="puddleShadow" dx="0" dy="3" result="puddleShadowOff"/>
         <feGaussianBlur in="SourceAlpha" stdDeviation="1.4" result="bump"/>
-        <feSpecularLighting in="bump" surfaceScale="6" specularConstant="1.7"
+        <feSpecularLighting in="bump" surfaceScale="6" specularConstant="0"
                             specularExponent="28" lighting-color="#ffffff" result="spec">
           <fePointLight x="500" y="-400" z="420"/>
         </feSpecularLighting>

src/styles.css

@@ -639,6 +639,17 @@ body.paint-white .cta-btn::before {
   -webkit-filter: url(#paintGlossWhiteBtn);
 }
 
+/* Header / quiz-progress-bar logos follow the active paint colour so
+   the small wordmark stays in sync with the hero as the user plays
+   with the modifier. Reads --mod-fill (set by the fill picker) and
+   falls back to the variant's default. White paint is intentionally
+   excluded — a near-white logo would vanish against the light
+   site-header background. */
+body.paint-green .logo,
+body.paint-green .qpb-logo {
+  color: var(--mod-fill, #2a3010);
+}
+
 /* Paint picker UI — top-right swatches */
 .paint-picker { display: flex; gap: 8px; align-items: center; }
 .paint-swatch {