feat: implement PWA scaffold, dark design system, and 3-tab glassmorphism nav

- Add @serwist/next for PWA service worker (precaching, offline support)
- Create public/manifest.json with dark theme (#0a0a0f) and SVG icons
- Rewrite globals.css with full dark premium design system (Tailwind v4)
  - Design tokens: bg-deep, bg-card, gold, nur-purple, emerald, borders, text
  - Utility classes: .glass, .glass-light, .gold-gradient, .nur-gradient, .gold-purple-gradient
  - Prayer ring SVG styles
- Replace old 5-tab nav with 3-tab floating glassmorphism pill
  - Home (House), Nur center raised 56px gold-purple circle, Profile (User)
  - Active gold #D4AF37, inactive #666, safe-area-aware
- Create src/lib/api/wordpress.ts fetchAPI wrapper with JWT auth
- Update layout.tsx with manifest, apple-web-app, Viewport export

public/icons/icon-192.svg

@@ -0,0 +1,5 @@
+<svg xmlns="http://www.w3.org/2000/svg" width="192" height="192" viewBox="0 0 192 192">
+  <rect width="192" height="192" rx="32" fill="#0a0a0f"/>
+  <path d="M86 36c-28 8-50 34-50 64 0 36 28 64 64 64 18 0 34-8 46-20-6 2-12 4-18 4-30 0-54-24-54-54 0-22 14-42 34-50l-22-8z" fill="#D4AF37"/>
+  <path d="M114 56l8 22 20 4-16 14 6 22-18-10-18 10 6-22-16-14 20-4z" fill="#A78BFA"/>
+</svg>

public/icons/icon-512.svg

@@ -0,0 +1,5 @@
+<svg xmlns="http://www.w3.org/2000/svg" width="512" height="512" viewBox="0 0 512 512">
+  <rect width="512" height="512" rx="64" fill="#0a0a0f"/>
+  <path d="M220 72c-74 20-130 90-130 170 0 96 76 172 172 172 48 0 90-20 122-54-16 6-32 10-48 10-82 0-146-64-146-146 0-58 36-110 90-134l-60-18z" fill="#D4AF37"/>
+  <path d="M308 144l20 58 54 10-42 36 14 58-48-26-48 26 14-58-42-36 54-10z" fill="#A78BFA"/>
+</svg>