refactor(home): unify section headings, differentiate capabilities and process

Reduce the "interchangeable cards" monotony flagged in Phase 0 and apply the
warm-premium type scale.

- SectionHeading: use the type scale (eyebrow via .eyebrow with brand tint,
  text-h2 title, body-lg description). Propagates to every home section.
- CapabilitiesSection: cleaner cards with a brand-tinted icon tile, type-scale
  title/body, soft elevation (drops the AppCard wrapper).
- ProcessSection: reworked into an editorial numbered timeline (large
  translucent brand numerals, top rule, no boxes) so it no longer looks
  identical to Capabilities.

Verified: eslint clean, no new type errors, tailwind generates the utilities.

components/home/section-heading.tsx

@@ -23,13 +23,13 @@ export function SectionHeading({
         className,
       )}
     >
-      <p className="text-xs font-semibold uppercase tracking-[0.16em] text-muted-foreground">
+      <p className="eyebrow text-caption font-medium text-brand-primary">
         {eyebrow}
       </p>
-      <h2 className="max-w-4xl text-balance text-3xl font-semibold tracking-[-0.05em] text-foreground sm:text-4xl lg:text-5xl">
+      <h2 className="max-w-4xl text-balance text-h2 text-foreground">
         {title}
       </h2>
-      <p className="max-w-3xl text-sm leading-7 text-muted-foreground sm:text-[1.02rem]">
+      <p className={cn("text-body-lg text-muted-foreground", align === "center" ? "mx-auto" : "max-w-2xl")}>
         {description}
       </p>
     </div>