Add budget module: FastAPI backend + React frontend

Backend: FastAPI + PostgreSQL with models for accounts, transactions,
and categories. Auto-categorization from merchant patterns, token auth,
CRUD endpoints, and seed data for 16 categories and 4 bank accounts.

Frontend: Login, Dashboard (account balances + recent charges),
Transactions (full CRUD table with search/filter), Cash & Transfers
view. Dark theme with emerald/cyan accents, responsive layout.

Infrastructure: Updated docker-compose for backend + db services,
nginx proxy config for API routing, deploy workflow with secrets.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

.github/workflows/deploy.yml

@@ -14,6 +14,12 @@ jobs:
       - name: Write .env.prod
         run: |
           cat > .env.prod << 'ENVEOF'
+          POSTGRES_USER=${{ secrets.POSTGRES_USER }}
+          POSTGRES_PASSWORD=${{ secrets.POSTGRES_PASSWORD }}
+          POSTGRES_DB=${{ secrets.POSTGRES_DB }}
+          SECRET_KEY=${{ secrets.SECRET_KEY }}
+          ADMIN_USERNAME=${{ secrets.ADMIN_USERNAME }}
+          ADMIN_PASSWORD=${{ secrets.ADMIN_PASSWORD }}
           LETSENCRYPT_EMAIL=${{ secrets.LETSENCRYPT_EMAIL }}
           ENVEOF
 
@@ -24,10 +30,10 @@ jobs:
 
       - name: Wait for health
         run: |
-          echo "Waiting for frontend..."
+          echo "Waiting for backend..."
           for i in $(seq 1 30); do
-            if docker inspect wealthysmart-frontend-prod --format '{{.State.Health.Status}}' 2>/dev/null | grep -q healthy; then
-              echo "Frontend is healthy"
+            if docker inspect wealthysmart-backend-prod --format '{{.State.Health.Status}}' 2>/dev/null | grep -q healthy; then
+              echo "Backend is healthy"
               break
             fi
             sleep 2