feat: migrate website-creator from Next.js+Payload to Astro+Tina CMS

Major changes:
- Replace Payload CMS with Tina CMS (self-hosted)
- Add Astro DB for consent logging (PDPA compliant)
- Update Tailwind v3 to v4 (@tailwindcss/vite plugin)
- Add astro-tina-starter template
- Rewrite consent template for Astro (ConsentBanner.astro, Astro DB, Nano Stores)
- Add install-tina-backend.sh for self-hosted Tina per customer
- Rename convert-astro.sh to migrate-tina.sh
- Add AGENTS.md template for generated websites
- Delete all Payload/Next.js files

Technical updates:
- Astro DB using defineDb with eq operators for queries
- Tailwind v4 with @theme block
- Tina CMS local development mode
- Proper Astro API routes for consent

Research-verified with official documentation (April 2026)

skills/website-creator/templates/astro-tina-starter/package.json

@@ -0,0 +1,38 @@
+{
+  "name": "astro-tina-starter",
+  "type": "module",
+  "version": "1.0.0",
+  "description": "Astro 6 + Tina CMS starter template with Tailwind CSS 4.x",
+  "scripts": {
+    "dev": "tinacms dev --port 3001 & astro dev",
+    "dev:astro": "astro dev",
+    "dev:tina": "tinacms dev --port 3001",
+    "build": "tinacms build && astro build",
+    "preview": "astro preview",
+    "astro": "astro",
+    "db:push": "astro db push",
+    "db:seed": "astro db seed"
+  },
+  "dependencies": {
+    "@astrojs/check": "^0.9.4",
+    "@astrojs/db": "^0.14.3",
+    "@nanostores/react": "^0.7.3",
+    "@tailwindcss/typography": "^0.5.15",
+    "@tailwindcss/vite": "^4.0.0",
+    "astro": "^6.1.7",
+    "nanostores": "^0.11.3",
+    "react": "^18.3.1",
+    "react-dom": "^18.3.1",
+    "tailwindcss": "^4.0.0",
+    "tina": "^2.1.4",
+    "tinacms": "^2.2.4",
+    "typescript": "^5.6.3"
+  },
+  "devDependencies": {
+    "@types/react": "^18.3.12",
+    "@types/react-dom": "^18.3.1"
+  },
+  "engines": {
+    "node": ">=20.0.0"
+  }
+}