feat: complete saleor core extensions app with React email templates

- Order confirmation, shipped, and cancelled email templates
- Uses @react-email/components for professional HTML emails
- Sends admin and customer notifications
- Integrates with Resend for email delivery
- Webhook handlers for ORDER_CREATED, ORDER_FULFILLED, ORDER_CANCELLED
- Docker image optimized for production
- Persistent auth data storage via PVC

.devcontainer/Dockerfile

@@ -0,0 +1,15 @@
+FROM mcr.microsoft.com/devcontainers/typescript-node:22
+
+ENV PNPM_HOME="/home/node/.pnpm"
+ENV PATH="$PNPM_HOME:$PATH"
+RUN corepack enable
+
+WORKDIR /app
+
+# This is needed so pnpm-store volume is created with correct permissions (see docker-compose.yml)
+RUN mkdir -p /app/.pnpm-store
+RUN chown -R node:node /app/.pnpm-store
+
+COPY package.json pnpm-lock.yaml ./
+RUN pnpm install --frozen-lockfile
+RUN chown -R node:node /home/node/.pnpm

.devcontainer/devcontainer.json

@@ -0,0 +1,23 @@
+{
+  "name": "Saleor app template",
+  "dockerComposeFile": "docker-compose.yml",
+  "service": "saleor-app-template",
+  "workspaceFolder": "/app",
+  "forwardPorts": [3000],
+  "portsAttributes": {
+    "3000": {
+      "label": "Saleor app"
+    }
+  },
+  "customizations": {
+    "vscode": {
+      "extensions": [
+        "dbaeumer.vscode-eslint",
+        "esbenp.prettier-vscode",
+        "GraphQL.vscode-graphql-syntax",
+        "GraphQL.vscode-graphql",
+        "streetsidesoftware.code-spell-checker"
+      ]
+    }
+  }
+}

.devcontainer/docker-compose.yml

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+services:
+  saleor-app-template:
+    image: saleor-app-template
+    command: sleep infinity # keeps docker container running
+    build:
+      context: ..
+      dockerfile: .devcontainer/Dockerfile
+    volumes:
+      - "..:/app"
+      - "pnpm-store:/app/.pnpm-store"
+
+volumes:
+  pnpm-store:
+    driver: local