facelift: fix light-theme scrims/thumbs - :global() the data-theme overrides

Astro scopes compound selectors, so [data-theme=light] .hero__scrim inside a component style
block could never match html[data-theme] - the light theme rendered dark scrims (embossed
low-contrast copy). Wrap the theme prefix in :global() in Hero, ProjectCard and the blog index.
Light 'blueprint' hero now reads clean.

src/pages/blog/index.astro

@@ -193,7 +193,7 @@ const featuredSeries = series[featured.id];
     z-index: 1;
     background: linear-gradient(90deg, var(--panel-solid) 0%, transparent 45%);
   }
-  [data-theme="light"] .featured__art::before {
+  :global([data-theme="light"]) .featured__art::before {
     background: linear-gradient(90deg, var(--panel-solid) 0%, transparent 45%);
     opacity: 0.85;
   }