New pattern submission- apigw-connect-notification pattern

**### Description:**
Adds the apigw-connect-notification pattern: an API Gateway sends in-app push notifications to Amazon Connect agents and admins through a direct AWS service integration via CreateNotification API.

Level: 200

Framework: SAM

Services: API Gateway, Amazon Connect

**What is Amazon Connect Notifications?**
In-app notifications are on-screen alerts in the Amazon Connect workspace header. They're the only built-in mechanism to broadcast messages to agents/admins regardless of what page they're on. **Currently Notifications can only be sent via the API there is no console UI to compose or send them.**

**Supported use cases:**
- System notifications: availability impacts, failover events, policy changes, critical feature updates
- Custom organizational messages: training reminders, schedule adherence alerts, emergency notifications

**How it works**

- A POST /notifications REST endpoint accepts a JSON body with recipients, localized content, and optional priority/TTL.
- API Gateway transforms the request via a VTL mapping template (camelCase → PascalCase) and calls the Connect CreateNotification API directly using a PUT integration.
- An IAM role grants API Gateway the connect:CreateNotification permission. No Lambda function sits in between.
- Notifications appear in the Connect header for targeted users within seconds.

### **Resources**
- [Amazon Connect Notifications - Admin Guide](https://docs.aws.amazon.com/connect/latest/adminguide/amazon-connect-notifications.html)
- [CreateNotification API Reference](https://docs.aws.amazon.com/connect/latest/APIReference/API_CreateNotification.html)
- [API Gateway AWS Service Integration](https://docs.aws.amazon.com/apigateway/latest/developerguide/getting-started-aws-proxy.html)

### Author bio may include a LinkedIn and/or Twitter reference and a 1-sentence bio. :
"name": "Vaidehi Patel",
"bio": "Solutions Architect at Amazon Web Services",
"linkedin": "https://www.linkedin.com/in/vaidehi-patel08/"

You must ensure that the sections of the model README.md are completed in full.

## GitHub PR for template:
https://github.com/aws-samples/serverless-patterns/pull/3287

Start with the linked template pull request and the pattern's README.md. Verify that the SAM pattern documents the POST /notifications endpoint, API Gateway mapping, direct Amazon Connect integration, and IAM permission described here. Done means the pattern and all required README.md sections are complete.

Written by the indexing model from the issue text.