feat: Extract Developer Portal as standalone Next.js app on port 3006

SDK customers can now access the documentation publicly without login.
The portal runs independently from admin-v2 on https://macmini:3006/.

- New developer-portal/ app with 26 pages, 2 components
- Docker service + nginx SSL reverse proxy on port 3006
- All /developers/* routes remapped to /* in the new app
- admin-v2 developer pages remain unchanged

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

developer-portal/tsconfig.json

@@ -0,0 +1,40 @@
+{
+  "compilerOptions": {
+    "lib": [
+      "dom",
+      "dom.iterable",
+      "esnext"
+    ],
+    "allowJs": true,
+    "skipLibCheck": true,
+    "strict": true,
+    "noEmit": true,
+    "esModuleInterop": true,
+    "module": "esnext",
+    "moduleResolution": "bundler",
+    "resolveJsonModule": true,
+    "isolatedModules": true,
+    "jsx": "preserve",
+    "incremental": true,
+    "plugins": [
+      {
+        "name": "next"
+      }
+    ],
+    "paths": {
+      "@/*": [
+        "./*"
+      ]
+    },
+    "target": "ES2017"
+  },
+  "include": [
+    "next-env.d.ts",
+    "**/*.ts",
+    "**/*.tsx",
+    ".next/types/**/*.ts"
+  ],
+  "exclude": [
+    "node_modules"
+  ]
+}