Prepare product layout and reusable Flutter theme

Relocate the existing Astro website and preserve its assets and hosting configuration. Add the consumer/backend scaffold and themed Flutter package with consumer tests. Related to #1.

website/package.json

@@ -0,0 +1,30 @@
+{
+  "name": "sxchnge",
+  "type": "module",
+  "version": "0.0.1",
+  "engines": {
+    "node": ">=22.12.0"
+  },
+  "scripts": {
+    "dev": "astro dev",
+    "build": "npm run tokens && astro build",
+    "preview": "astro preview",
+    "astro": "astro",
+    "tokens": "node scripts/generate-tokens.mjs",
+    "test": "node --test scripts/quote.test.mjs",
+    "check": "astro check",
+    "format": "prettier --write ."
+  },
+  "dependencies": {
+    "astro": "^7.3.1"
+  },
+  "allowScripts": {
+    "esbuild": true
+  },
+  "devDependencies": {
+    "@astrojs/check": "^0.9.10",
+    "prettier": "^3.9.6",
+    "prettier-plugin-astro": "^0.14.1",
+    "typescript": "^6.0.3"
+  }
+}