Fix dogfood pass-2: grid thumbs, AI view, featured/recent dedupe

- Portfolio cards: eager first-page load, cache-safe onLoad via ref,
  soft opacity while loading, error placeholder (no stuck black voids)
- Hide home view chips when primary category has zero projects (AI)
- Seed AI view with showOthers false; home Recent excludes Featured
- Slightly larger scroll-padding under sticky header

client/src/styles/global.scss

@@ -32,7 +32,7 @@
 html {
   scroll-behavior: smooth;
   /* Keep anchored content clear of sticky site header */
-  scroll-padding-top: calc(var(--header-h) + 0.75rem);
+  scroll-padding-top: calc(var(--header-h) + 1.25rem);
 }
 
 body {