feat(site): port stitch design system + seed-ready content model

Ports the "Technical Editorial" design sample into real TSX wired to
Payload globals/collections. Home/About/Projects (list+detail)/Contact
pages render against Payload data. Expands schemas (Home principles,
About timeline/skills/gear, Contact channels) to cover the full design
surface. Adds seed script that populates realistic AI-drafted content
for first boot. Defers writing/resume routes per scope cut.

- Design tokens: Material-3 palette + Space Grotesk/Inter typography
  scale + dot-grid + glassmorphism utilities
- Shared layout: Nav, Footer, StatusTerminal, GridOverlay, Button,
  TechChip in src/components/site
- Schemas: expand 5 globals + 6 collections; add auto-slug hook
- Seed: scripts/seed.ts — idempotent upsert for media, categories,
  6 projects, 8 gear, 3 posts, 5 globals; generates placeholder admin
- Contact: form + /api/contact route with optional Turnstile verify
- Rename TURNSTILE_SITE_KEY -> NEXT_PUBLIC_TURNSTILE_SITE_KEY (client)
- Remove dead src/components/SiteHeader|SiteFooter|StatusTerminal

src/components/site/TechChip.tsx

@@ -0,0 +1,25 @@
+import type { ReactNode } from "react";
+
+type Accent = "secondary" | "tertiary" | "primary";
+
+interface TechChipProps {
+  children: ReactNode;
+  accent?: Accent;
+  className?: string;
+}
+
+const accentClasses: Record<Accent, string> = {
+  primary: "text-primary",
+  secondary: "text-secondary",
+  tertiary: "text-tertiary",
+};
+
+export function TechChip({ children, accent = "secondary", className = "" }: TechChipProps) {
+  return (
+    <span
+      className={`inline-flex items-center rounded-sm bg-surface-container-highest px-2.5 py-1 label-sm ${accentClasses[accent]} ${className}`}
+    >
+      {children}
+    </span>
+  );
+}