Bygg NeuroSemantics AI: minimal mobilapp, en backend, IaC och CI/CD

Ersätter den tidigare webappen på denna branch med ett fokuserat monorepo:

- apps/mobile: Expo/React Native med tre vyer (Welcome, Chat, Paywall),
  Cognito hosted UI-inloggning (Apple/Google/e-post) och In-App
  Purchase/Play Billing via en gemensam purchases-modul.
- services/api: en enda Lambda-backend — OpenAI Responses API med
  Markdown-kunskapsbas som systeminstruktioner, free tier-gräns i
  PostgreSQL (HTTP 402 -> paywall) och kvittoverifiering bakom ett
  delat PaymentProvider-interface (Apple/Google, Stripe kan läggas
  till för webb senare).
- infra: AWS CDK-stack med API Gateway (JWT-authorizer), Lambda,
  Cognito, Aurora Serverless v2 och Secrets Manager.
- db/migrations: minimal datamodell (users + usage), inga
  konversationer sparas.
- GitHub Actions: CI (lint, typecheck, test) och deploy från main.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_0118DaxZR36RpnY524vRqx3z

apps/mobile/app.json

@@ -0,0 +1,28 @@
+{
+  "expo": {
+    "name": "NeuroSemantics AI",
+    "slug": "neurosemantics-ai",
+    "version": "1.0.0",
+    "orientation": "portrait",
+    "scheme": "neurosemantics",
+    "userInterfaceStyle": "light",
+    "backgroundColor": "#F7F6F2",
+    "ios": {
+      "bundleIdentifier": "com.neurosemantics.app",
+      "supportsTablet": false,
+      "usesAppleSignIn": true
+    },
+    "android": {
+      "package": "com.neurosemantics.app"
+    },
+    "extra": {
+      "apiUrl": "https://REPLACE_WITH_API_URL",
+      "cognitoDomain": "https://REPLACE_WITH_PREFIX.auth.eu-north-1.amazoncognito.com",
+      "cognitoClientId": "REPLACE_WITH_CLIENT_ID",
+      "iosMonthlyProductId": "neurosemantics_monthly",
+      "iosYearlyProductId": "neurosemantics_yearly",
+      "androidMonthlyProductId": "neurosemantics_monthly",
+      "androidYearlyProductId": "neurosemantics_yearly"
+    }
+  }
+}