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

.github/workflows/ci.yml

@@ -0,0 +1,21 @@
+name: CI
+
+on:
+  pull_request:
+  push:
+    branches: [main]
+
+jobs:
+  check:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+      - uses: actions/setup-node@v4
+        with:
+          node-version: 22
+          cache: npm
+      - run: npm ci
+      - run: npm run lint
+      - run: npm run format:check
+      - run: npm run typecheck
+      - run: npm test

.github/workflows/deploy.yml

@@ -0,0 +1,28 @@
+name: Deploy
+
+on:
+  push:
+    branches: [main]
+
+concurrency: deploy
+
+permissions:
+  id-token: write
+  contents: read
+
+jobs:
+  deploy:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+      - uses: actions/setup-node@v4
+        with:
+          node-version: 22
+          cache: npm
+      - run: npm ci
+      - uses: aws-actions/configure-aws-credentials@v4
+        with:
+          role-to-assume: ${{ secrets.AWS_DEPLOY_ROLE_ARN }}
+          aws-region: ${{ vars.AWS_REGION || 'eu-north-1' }}
+      - run: npx cdk deploy --require-approval never
+        working-directory: infra